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  • How can I turn a SimpleXML object to array, then shuffle?

    - by Joshua Cody
    Crux of my problem: I've got an XML file that returns 20 results. Within these results are all the elements I need to get. Now, I need to return them in a random order, and be able to specifically work with item 1, items 2-5, and items 6-17. Idea 1: Use this script to convert the object to an array, which I can shuffle through. This is close to working, but a few of the elements I need to get are under a different namespace, and I don't seem to be able to get them. Code: /* * Convert a SimpleXML object into an array (last resort). * * @access public * @param object $xml * @param boolean $root - Should we append the root node into the array * @return array */ function xmlToArray($xml, $root = true) { if (!$xml->children()) { return (string)$xml; } $array = array(); foreach ($xml->children() as $element => $node) { $totalElement = count($xml->{$element}); if (!isset($array[$element])) { $array[$element] = ""; } // Has attributes if ($attributes = $node->attributes()) { $data = array( 'attributes' => array(), 'value' => (count($node) > 0) ? xmlToArray($node, false) : (string)$node // 'value' => (string)$node (old code) ); foreach ($attributes as $attr => $value) { $data['attributes'][$attr] = (string)$value; } if ($totalElement > 1) { $array[$element][] = $data; } else { $array[$element] = $data; } // Just a value } else { if ($totalElement > 1) { $array[$element][] = xmlToArray($node, false); } else { $array[$element] = xmlToArray($node, false); } } } if ($root) { return array($xml->getName() => $array); } else { return $array; } } $thumbfeed = simplexml_load_file('http://gdata.youtube.com/feeds/api/videos?q=skadaddlemedia&max-results=20&orderby=published&prettyprint=true'); $xmlToArray = xmlToArray($thumbfeed); $thumbArray = $xmlToArray["feed"]; for($n = 0; $n < 18; $n++){ $title = $thumbArray["entry"][$n]["title"]["value"]; $desc = $thumbArray["entry"][0]["content"]["value"]; $videoUrl = $differentNamespace; $thumbUrl = $differentNamespace; } Idea 2: Continue using my working code that is getting the information using a foreach, but store each element in an array, then use shuffle on that. I'm not precisely sure hwo to write to an array within a foreach loop and not write over one another, though. Working code: foreach($thumbfeed->entry as $entry){ $thumbmedia = $entry->children('http://search.yahoo.com/mrss/') ->group ; $thumb = $thumbmedia->thumbnail[0]->attributes()->url; $thumburl = $thumbmedia->content[0]->attributes()->url; $thumburl1 = explode("http://www.youtube.com/v/", $thumburl[0]); $thumbid = explode("?f=videos&app=youtube_gdata", $thumburl1[1]); $thumbtitle = $thumbmedia->title; $thumbyt = $thumbmedia->children('http://gdata.youtube.com/schemas/2007') ->duration ; $thumblength = $thumbyt->attributes()->seconds; } Ideas on if either of these are good solutions to my problem, and if so, how I can get over my execution humps? Thanks so much for any help you can give.

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  • Best way to get back to using the power of lxml after having to use a regex to find something in an

    - by PyNEwbie
    I am trying to rip some text out of a large number of html documents (numbers in the hundreds of thousands). The documents are really forms but they are prepared by a very large group of different organizations so there is significant variation in how they create the document. For example, the documents are divided into chapters. I might want to extract the contents of Chapter 5 from every document so I can analyze the content of the chapter. Initially I thought this would be easy but it turns out that the authors might use a set of non-nested tables throughout the document to hold the content so that Chapter n could be displayed using td tags inside a table. Or they might use other elements such as p tags H tags, div tags or any other block level element. After trying repeatedly to use lxml to help me identify the beginning and end of each chapter I have determined that it is a lot cleaner to use a regular expression because in every case, no matter what the enclosing html element is the chapter label is always in the form of >Chapter # It is a little more complicated in that there might be some white space or non-breaking space represented in different ways (  or   or just spaces). Nonetheless it was trivial to write a regular expression to identify the beginning of each section. (The beginning of one section is the end of the previous section.) But now I want to use lxml to get the text out. My thought is that I have really no choice but to walk along my string to find the close tag for the element that encloses the text I am using to find the relevant section. That is here is one example where the element holding the Chapter name is a div <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Chapter 1.&#160;&#160;&#160;Our Beginnings.</font></div> So I am imagining that I would begin at the location where I found the match for chapter 1 and set up a regular expressions to find the next </div|</td|</p|</h1 . . . So at this point I have identified the type of element holding my chapter heading I can use the same logic to find all of the text that is within that element that is set up a regular expression to help me mark from >Chapter 1.&#160;&#160;&#160;Our Beginnings.< So I have identified where my Chapter 1 begins I can do the same for chapter 2 (which is where Chapter 1 ends) Now I am imagining that I am going to snip the document beginning at the opening of the element that I identified as the element the indicates where chapter 1 begins and ending just before the opening of the element that I identified as the element that indicates where Chapter 2 begins. The string that I have identified will then be fed to lxml to use its power to get the content. I am going to all of this trouble because I have read over and over - never use a regular expression to extract content from html documents and I have not hit on a way to be as accurate with lxml to identify the starting and ending locations for the text I want to extract. For example, I can never be certain that the subtitle of Chapter 1 is Our Beginnings it could be Our Red Canary. Let me say that I spent two solid days trying with lxml to be confident that I had the beginning and ending elements and I could only be accurate <60% of the time but a very short regular expression has given me better than 95% success. I have a tendency to make things more complicated than necessary so I am wondering if anyone has seen or solved a similar problems and if they had an approach (not the details mind you) that they would like to offer.

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  • Flash Media Server Streaming: Content Protection

    - by dbemerlin
    Hi, i have to implement flash streaming for the relaunch of our video-on-demand system but either because i haven't worked with flash-related systems before or because i'm too stupid i cannot get the system to work as it has to. We need: Per file & user access control with checks on a WebService every minute if the lease time ran out mid-stream: cancelling the stream rtmp streaming dynamic bandwidth checking Video Playback with Flowplayer (existing license) I've got the streaming and bandwidth check working, i just can't seem to get the access control working. I have no idea how i know which file is played back or how i can play back a file depending on a key the user has entered. Server-Side Code (main.asc): application.onAppStart = function() { trace("Starting application"); this.payload = new Array(); for (var i=0; i < 1200; i++) { this.payload[i] = Math.random(); //16K approx } } application.onConnect = function( p_client, p_autoSenseBW ) { p_client.writeAccess = ""; trace("client at : " + p_client.uri); trace("client from : " + p_client.referrer); trace("client page: " + p_client.pageUrl); // try to get something from the query string: works var i = 0; for (i = 0; i < p_client.uri.length; ++i) { if (p_client.uri[i] == '?') { ++i; break; } } var loadVars = new LoadVars(); loadVars.decode(p_client.uri.substr(i)); trace(loadVars.toString()); trace(loadVars['foo']); // And accept the connection this.acceptConnection(p_client); trace("accepted!"); //this.rejectConnection(p_client); // A connection from Flash 8 & 9 FLV Playback component based client // requires the following code. if (p_autoSenseBW) { p_client.checkBandwidth(); } else { p_client.call("onBWDone"); } trace("Done connecting"); } application.onDisconnect = function(client) { trace("client disconnecting!"); } Client.prototype.getStreamLength = function(p_streamName) { trace("getStreamLength:" + p_streamName); return Stream.length(p_streamName); } Client.prototype.checkBandwidth = function() { application.calculateClientBw(this); } application.calculateClientBw = function(p_client) { /* lots of lines copied from an adobe sample, appear to work */ } Client-Side Code: <head> <script type="text/javascript" src="flowplayer-3.1.4.min.js"></script> </head> <body> <a class="rtmp" href="rtmp://xx.xx.xx.xx/vod_project/test_flv.flv" style="display: block; width: 520px; height: 330px" id="player"> </a> <script> $f( "player", "flowplayer-3.1.5.swf", { clip: { provider: 'rtmp', autoPlay: false, url: 'test_flv' }, plugins: { rtmp: { url: 'flowplayer.rtmp-3.1.3.swf', netConnectionUrl: 'rtmp://xx.xx.xx.xx/vod_project?foo=bar' } } } ); </script> </body> My first Idea was to get a key from the Query String, ask the web service about which file and user that key is for and play the file but i can't seem to find out how to play a file from server side. My second idea was to let flowplayer play a file, pass the key as query string and if the filename and key don't match then reject the connection but i can't seem to find out which file it's currently playing. The only remaining idea i have is: create a list of all files the user is allowed to open and set allowReadAccess or however it was called to allow those files, but that would be clumsy due to the current infrastructure. Any hints? Thanks.

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  • Bridging LXC containers to host eth0 so they can have a public IP

    - by Vianney Stroebel
    UPDATE: I found the solution there: http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge#No_traffic_gets_trough_.28except_ARP_and_STP.29 # cd /proc/sys/net/bridge # ls bridge-nf-call-arptables bridge-nf-call-iptables bridge-nf-call-ip6tables bridge-nf-filter-vlan-tagged # for f in bridge-nf-*; do echo 0 $f; done But I'd like to have expert opinions on this: is it safe to disable all bridge-nf-*? What are they here for? END OF UPDATE I need to bridge LXC containers to the physical interface (eth0) of my host, reading numerous tutorials, documents and blog posts on the subject. I need the containers to have their own public IP (which I've previously done KVM/libvirt). After two days of searching and trying, I still can't make it work with LXC containers. The host runs a freshly installed Ubuntu Server Quantal (12.10) with only libvirt (which I'm not using here) and lxc installed. I created the containers with : lxc-create -t ubuntu -n mycontainer So they also run Ubuntu 12.10. Content of /var/lib/lxc/mycontainer/config is: lxc.utsname = mycontainer lxc.mount = /var/lib/lxc/test/fstab lxc.rootfs = /var/lib/lxc/test/rootfs lxc.network.type = veth lxc.network.flags = up lxc.network.link = br0 lxc.network.name = eth0 lxc.network.veth.pair = vethmycontainer lxc.network.ipv4 = 179.43.46.233 lxc.network.hwaddr= 02:00:00:86:5b:11 lxc.devttydir = lxc lxc.tty = 4 lxc.pts = 1024 lxc.arch = amd64 lxc.cap.drop = sys_module mac_admin mac_override lxc.pivotdir = lxc_putold # uncomment the next line to run the container unconfined: #lxc.aa_profile = unconfined lxc.cgroup.devices.deny = a # Allow any mknod (but not using the node) lxc.cgroup.devices.allow = c *:* m lxc.cgroup.devices.allow = b *:* m # /dev/null and zero lxc.cgroup.devices.allow = c 1:3 rwm lxc.cgroup.devices.allow = c 1:5 rwm # consoles lxc.cgroup.devices.allow = c 5:1 rwm lxc.cgroup.devices.allow = c 5:0 rwm #lxc.cgroup.devices.allow = c 4:0 rwm #lxc.cgroup.devices.allow = c 4:1 rwm # /dev/{,u}random lxc.cgroup.devices.allow = c 1:9 rwm lxc.cgroup.devices.allow = c 1:8 rwm lxc.cgroup.devices.allow = c 136:* rwm lxc.cgroup.devices.allow = c 5:2 rwm # rtc lxc.cgroup.devices.allow = c 254:0 rwm #fuse lxc.cgroup.devices.allow = c 10:229 rwm #tun lxc.cgroup.devices.allow = c 10:200 rwm #full lxc.cgroup.devices.allow = c 1:7 rwm #hpet lxc.cgroup.devices.allow = c 10:228 rwm #kvm lxc.cgroup.devices.allow = c 10:232 rwm Then I changed my host /etc/network/interfaces to: auto lo iface lo inet loopback auto br0 iface br0 inet static bridge_ports eth0 bridge_fd 0 address 92.281.86.226 netmask 255.255.255.0 network 92.281.86.0 broadcast 92.281.86.255 gateway 92.281.86.254 dns-nameservers 213.186.33.99 dns-search ovh.net When I try command line configuration ("brctl addif", "ifconfig eth0", etc.) my remote host becomes inaccessible and I have to hard reboot it. I changed the content of /var/lib/lxc/mycontainer/rootfs/etc/network/interfaces to: auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 179.43.46.233 netmask 255.255.255.255 broadcast 178.33.40.233 gateway 92.281.86.254 It takes several minutes for mycontainer to start (lxc-start -n mycontainer). I tried replacing gateway 92.281.86.254 by : post-up route add 92.281.86.254 dev eth0 post-up route add default gw 92.281.86.254 post-down route del 92.281.86.254 dev eth0 post-down route del default gw 92.281.86.254 My container then starts instantly. But whatever configuration I set in /var/lib/lxc/mycontainer/rootfs/etc/network/interfaces, I cannot ping from mycontainer to any IP (including the host's) : ubuntu@mycontainer:~$ ping 92.281.86.226 PING 92.281.86.226 (92.281.86.226) 56(84) bytes of data. ^C --- 92.281.86.226 ping statistics --- 6 packets transmitted, 0 received, 100% packet loss, time 5031ms And my host cannot ping the container: root@host:~# ping 179.43.46.233 PING 179.43.46.233 (179.43.46.233) 56(84) bytes of data. ^C --- 179.43.46.233 ping statistics --- 5 packets transmitted, 0 received, 100% packet loss, time 4000ms My container's ifconfig: ubuntu@mycontainer:~$ ifconfig eth0 Link encap:Ethernet HWaddr 02:00:00:86:5b:11 inet addr:179.43.46.233 Bcast:255.255.255.255 Mask:0.0.0.0 inet6 addr: fe80::ff:fe79:5a31/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:64 errors:0 dropped:6 overruns:0 frame:0 TX packets:54 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:4070 (4.0 KB) TX bytes:4168 (4.1 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:32 errors:0 dropped:0 overruns:0 frame:0 TX packets:32 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:2496 (2.4 KB) TX bytes:2496 (2.4 KB) My host's ifconfig: root@host:~# ifconfig br0 Link encap:Ethernet HWaddr 4c:72:b9:43:65:2b inet addr:92.281.86.226 Bcast:91.121.67.255 Mask:255.255.255.0 inet6 addr: fe80::4e72:b9ff:fe43:652b/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1453 errors:0 dropped:18 overruns:0 frame:0 TX packets:1630 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:145125 (145.1 KB) TX bytes:299943 (299.9 KB) eth0 Link encap:Ethernet HWaddr 4c:72:b9:43:65:2b UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3178 errors:0 dropped:0 overruns:0 frame:0 TX packets:1637 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:298263 (298.2 KB) TX bytes:309167 (309.1 KB) Interrupt:20 Memory:fe500000-fe520000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:6 errors:0 dropped:0 overruns:0 frame:0 TX packets:6 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:300 (300.0 B) TX bytes:300 (300.0 B) vethtest Link encap:Ethernet HWaddr fe:0d:7f:3e:70:88 inet6 addr: fe80::fc0d:7fff:fe3e:7088/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:54 errors:0 dropped:0 overruns:0 frame:0 TX packets:67 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:4168 (4.1 KB) TX bytes:4250 (4.2 KB) virbr0 Link encap:Ethernet HWaddr de:49:c5:66:cf:84 inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) I have disabled lxcbr0 (USE_LXC_BRIDGE="false" in /etc/default/lxc). root@host:~# brctl show bridge name bridge id STP enabled interfaces br0 8000.4c72b943652b no eth0 vethtest I have configured the IP 179.43.46.233 to point to 02:00:00:86:5b:11 in my hosting provider (OVH) config panel. (The IPs in this post are not the real ones.) Thanks for reading this long question! :-) Vianney

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  • use .net webbrowser control by multithread, throw "EXCEPTION code=ACCESS_VIOLATION"

    - by user1507827
    i want to make a console program to monitor a webpage's htmlsourcecode, because some of the page content are created by some javescript, so i have to use webbrowser control. like : View Generated Source (After AJAX/JavaScript) in C# my code is below: public class WebProcessor { public string GeneratedSource; public string URL ; public DateTime beginTime; public DateTime endTime; public object GetGeneratedHTML(object url) { URL = url.ToString(); try { Thread[] t = new Thread[10]; for (int i = 0; i < 10; i++) { t[i] = new Thread(new ThreadStart(WebBrowserThread)); t[i].SetApartmentState(ApartmentState.STA); t[i].Name = "Thread" + i.ToString(); t[i].Start(); //t[i].Join(); } } catch (Exception ex) { Console.WriteLine(ex.ToString()); } return GeneratedSource; } private void WebBrowserThread() { WebBrowser wb = new WebBrowser(); wb.ScriptErrorsSuppressed = true; wb.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler( wb_DocumentCompleted); while(true ) { beginTime = DateTime.Now; wb.Navigate(URL); while (wb.ReadyState != WebBrowserReadyState.Complete) { Thread.Sleep(new Random().Next(10,100)); Application.DoEvents(); } } //wb.Dispose(); } private void wb_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) { WebBrowser wb = (WebBrowser)sender; if (wb.ReadyState == WebBrowserReadyState.Complete) { GeneratedSource= wb.Document.Body.InnerHtml; endTime = DateTime.Now; Console.WriteLine("WebBrowser " + (endTime-beginTime).Milliseconds + Thread.CurrentThread.Name + wb.Document.Title); } } } when it run, after a while (20-50 times), it throw the exception like this EXCEPTION code=ACCESS_VIOLATION (null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(nul l)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(n ull)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null) (null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(null)(nul l)(null)BACKTRACE: 33 stack frames: #0 0x083dba8db0 at MatchExactGetIDsOfNames in mshtml.dll #1 0x0879f9b837 at StrongNameErrorInfo in mscorwks.dll #2 0x0879f9b8e3 at StrongNameErrorInfo in mscorwks.dll #3 0x0879f9b93a at StrongNameErrorInfo in mscorwks.dll #4 0x0879f9b9e0 at StrongNameErrorInfo in mscorwks.dll #5 0x0879f9b677 at StrongNameErrorInfo in mscorwks.dll #6 0x0879f9b785 at StrongNameErrorInfo in mscorwks.dll #7 0x0879f192a8 at InstallCustomModule in mscorwks.dll #8 0x0879f19444 at InstallCustomModule in mscorwks.dll #9 0x0879f194ab at InstallCustomModule in mscorwks.dll #10 0x0879fa6491 at StrongNameErrorInfo in mscorwks.dll #11 0x0879f44bcf at DllGetClassObjectInternal in mscorwks.dll #12 0x089bbafa at in #13 0x087b18cc10 at in System.Windows.Forms.ni.dll #14 0x087b91f4c1 at in System.Windows.Forms.ni.dll #15 0x08d00669 at in #16 0x08792d6e46 at in mscorlib.ni.dll #17 0x08792e02cf at in mscorlib.ni.dll #18 0x08792d6dc4 at in mscorlib.ni.dll #19 0x0879e71b4c at in mscorwks.dll #20 0x0879e896ce at in mscorwks.dll #21 0x0879e96ea9 at CoUninitializeEE in mscorwks.dll #22 0x0879e96edc at CoUninitializeEE in mscorwks.dll #23 0x0879e96efa at CoUninitializeEE in mscorwks.dll #24 0x0879f88357 at GetPrivateContextsPerfCounters in mscorwks.dll #25 0x0879e9cc8f at CoUninitializeEE in mscorwks.dll #26 0x0879e9cc2b at CoUninitializeEE in mscorwks.dll #27 0x0879e9cb51 at CoUninitializeEE in mscorwks.dll #28 0x0879e9ccdd at CoUninitializeEE in mscorwks.dll #29 0x0879f88128 at GetPrivateContextsPerfCounters in mscorwks.dll #30 0x0879f88202 at GetPrivateContextsPerfCounters in mscorwks.dll #31 0x0879f0e255 at InstallCustomModule in mscorwks.dll #32 0x087c80b729 at GetModuleFileNameA in KERNEL32.dll i have try lots of methods to solve the problem, finally, i found that if i thread sleep more millseconds, it will run for a longer time, but the exception is still throw. hope somebody give me the answer of how to slove ... thanks very much !!!

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  • Detecting Acceleration in a car (iPhone Accelerometer)

    - by TheGazzardian
    Hello, I am working on an iPhone app where we are trying to calculate the acceleration of a moving car. Similar apps have accomplished this (Dynolicious), but the difference is that this app is designed to be used during general city driving, not on a drag strip. This leads us to one big concern that Dynolicious was luckily able to avoid: hills. Yes, hills. There are two important stages to this: calibration, and actual driving. Our initial run was simple and suffered the consequences. During the calibration stage, I took the average force on the phone, and during running, I just subtracted the average force from the current force to get the current acceleration this frame. The problem with this is that the typical car receives much more force than just the forward force - everything from turning to potholes was causing the values to go out of sync with what was really happening. The next run was to add the condition that the iPhone must be oriented in such a way that the screen was facing toward the back of the car. Using this method, I attempted to follow only force on the z-axis, but this obviously lead to problems unless the iPhone was oriented directly upright, because of gravity. Some trigonometry later, and I had managed to work gravity out of the equation, so that the car was actually being read very, very well by the iPhone. Until I hit a slope. As soon as the angle of the car changed, suddenly I was receiving accelerations and decelerations that didn't make sense, and we were once again going out of sync. Talking with someone a lot smarter than me at math lead to a solution that I have been trying to implement for longer than I would like to admit. It's steps are as follows: 1) During calibration, measure gravity as a vector instead of a size. Store that vector. 2) When the car initially moves forward, take the vector of motion and subtract gravity. Use this as the forward momentum. (Ignore, for now, the user cases where this will be difficult and let's concentrate on the math :) 3) From the forward vector and the gravity vector, construct a plane. 4) Whenever a force is received, project it onto said plane to get rid of sideways force/etc. 5) Then, use that force, the known magnitude of gravity, and the known direction of forward motion to essentially solve a triangle to get the forward vector. The problem that is causing the most difficulty in this new system is not step 5, which I have gotten to the point where all the numbers look as they should. The difficult part is actually the detection of the forward vector. I am selecting vectors whose magnitude exceeds gravity, and from there, averaging them and subtracting gravity. (I am doing some error checking to make sure that I am not using a force just because the iPhone accelerometer was off by a bit, which happens more frequently than I would like). But if I plot these vectors that I am using, they actually vary by an angle of about 20-30 degrees, which can lead to some strong inaccuracies. The end result is that the app is even more inaccurate now than before. So basically - all you math and iPhone brains out there - any glaring errors? Any potentially better solutions? Any experience that could be useful at all? Award: offering a bounty of $250 to the first answer that leads to a solution.

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  • What are good CLI tools for JSON?

    - by jasonmp85
    General Problem Though I may be diagnosing the root cause of an event, determining how many users it affected, or distilling timing logs in order to assess the performance and throughput impact of a recent code change, my tools stay the same: grep, awk, sed, tr, uniq, sort, zcat, tail, head, join, and split. To glue them all together, Unix gives us pipes, and for fancier filtering we have xargs. If these fail me, there's always perl -e. These tools are perfect for processing CSV files, tab-delimited files, log files with a predictable line format, or files with comma-separated key-value pairs. In other words, files where each line has next to no context. XML Analogues I recently needed to trawl through Gigabytes of XML to build a histogram of usage by user. This was easy enough with the tools I had, but for more complicated queries the normal approaches break down. Say I have files with items like this: <foo user="me"> <baz key="zoidberg" value="squid" /> <baz key="leela" value="cyclops" /> <baz key="fry" value="rube" /> </foo> And let's say I want to produce a mapping from user to average number of <baz>s per <foo>. Processing line-by-line is no longer an option: I need to know which user's <foo> I'm currently inspecting so I know whose average to update. Any sort of Unix one liner that accomplishes this task is likely to be inscrutable. Fortunately in XML-land, we have wonderful technologies like XPath, XQuery, and XSLT to help us. Previously, I had gotten accustomed to using the wonderful XML::XPath Perl module to accomplish queries like the one above, but after finding a TextMate Plugin that could run an XPath expression against my current window, I stopped writing one-off Perl scripts to query XML. And I just found out about XMLStarlet which is installing as I type this and which I look forward to using in the future. JSON Solutions? So this leads me to my question: are there any tools like this for JSON? It's only a matter of time before some investigation task requires me to do similar queries on JSON files, and without tools like XPath and XSLT, such a task will be a lot harder. If I had a bunch of JSON that looked like this: { "firstName": "Bender", "lastName": "Robot", "age": 200, "address": { "streetAddress": "123", "city": "New York", "state": "NY", "postalCode": "1729" }, "phoneNumber": [ { "type": "home", "number": "666 555-1234" }, { "type": "fax", "number": "666 555-4567" } ] } And wanted to find the average number of phone numbers each person had, I could do something like this with XPath: fn:avg(/fn:count(phoneNumber)) Questions Are there any command-line tools that can "query" JSON files in this way? If you have to process a bunch of JSON files on a Unix command line, what tools do you use? Heck, is there even work being done to make a query language like this for JSON? If you do use tools like this in your day-to-day work, what do you like/dislike about them? Are there any gotchas? I'm noticing more and more data serialization is being done using JSON, so processing tools like this will be crucial when analyzing large data dumps in the future. Language libraries for JSON are very strong and it's easy enough to write scripts to do this sort of processing, but to really let people play around with the data shell tools are needed. Related Questions Grep and Sed Equivalent for XML Command Line Processing Is there a query language for JSON? JSONPath or other XPath like utility for JSON/Javascript; or Jquery JSON

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  • Where do I start ?

    - by Panthe
    Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be learning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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  • Right code to retrieve data from sql server database

    - by HasanGursoy
    Hi, I have some problems in database connection and wonder if I have something wrong in my code. Please review. This question is related: Switch between databases, use two databases simultaneously question. cs="Data Source=mywebsite.com;Initial Catalog=database;User Id=root;Password=toor;Connect Timeout=10;Pooling='true';" using (SqlConnection cnn = new SqlConnection(WebConfigurationManager.ConnectionStrings["cs"].ConnectionString)) { using (SqlCommand cmmnd = new SqlCommand("", cnn)) { try { cnn.Open(); #region Header & Description cmmnd.Parameters.Add("@CatID", SqlDbType.Int).Value = catId; cmmnd.CommandText = "SELECT UpperID, Title, Description FROM Categories WHERE CatID=@CatID;"; string mainCat = String.Empty, rootCat = String.Empty; using (SqlDataReader rdr = cmmnd.ExecuteReader()) { if (rdr.Read()) { mainCat = rdr["Title"].ToString(); upperId = Convert.ToInt32(rdr["UpperID"]); description = rdr["Title"]; } else { Response.Redirect("/", false); } } if (upperId > 0) //If upper category exists add its name { cmmnd.Parameters["@CatID"].Value = upperId; cmmnd.CommandText = "SELECT Title FROM Categories WHERE CatID=@CatID;"; using (SqlDataReader rdr = cmmnd.ExecuteReader()) { if (rdr.Read()) { rootCat = "<a href='x.aspx'>" + rdr["Title"] + "</a> &raquo; "; } } } #endregion #region Sub-Categories if (upperId == 0) //show only at root categories { cmmnd.Parameters["@CatID"].Value = catId; cmmnd.CommandText = "SELECT Count(CatID) FROM Categories WHERE UpperID=@CatID;"; if (Convert.ToInt32(cmmnd.ExecuteScalar()) > 0) { cmmnd.CommandText = "SELECT CatID, Title FROM Categories WHERE UpperID=@CatID ORDER BY Title;"; using (SqlDataReader rdr = cmmnd.ExecuteReader()) { while (rdr.Read()) { subcat.InnerHtml += "<a href='x.aspx'>" + rdr["Title"].ToString().ToLower() + "</a>\n"; description += rdr["Title"] + ", "; } } } } #endregion } catch (Exception ex) { HasanG.LogException(ex, Request.RawUrl, HttpContext.Current); Response.Redirect("/", false); } finally { cnn.Close(); } } } The random errors I'm receiving are: A transport-level error has occurred when sending the request to the server. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.) A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server) Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached. Cannot open database "db" requested by the login. The login failed. Login failed for user 'root'.

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  • QGraphicsView and custom Cursors

    - by Etienne de Martel
    I am trying to make use of a mix of custom cursors and preset cursors for my QGraphicsView. In my implementation we have created a notion of "modes" for the view. Meaning that depending on what "mode" the user is in, different things will happen on the left-click, or left-click drag. Anyway, none of that is the problem, just the context. The problem arises when I try to change the cursor for each mode. For instance, for mode 1 we want to show the regular Arrow cursor, but for mode 2, we want to use a custom pixmap. Seemingly simple we call graphicsview->viewport()->setCursor(Qt::QArrowCursor)  when we are switching to mode 1, and graphicsview->viewport()->setCursor(our custom cursor) for mode 2. Except it doesn't work at all. Firstly, the cursor does not change to the custom cursor. That is the first problem. However, if through another operation the drag mode of the graphics view gets set to ScrollHandDrag, the cursor will switch to the custom cursor once the drag operation is complete. Weird. But the plot thickens... Once we switch to the custom cursor, it can never be changed back to the ArrorCursor no matter how many times we call setCursor(Qt::QArrowCursor). it also doesn't seem to matter whether I call setCursor on the viewport or the graphics view itself. So, just for fun, I added a call to graphicsview->unsetCursor() just before we want to change the cursor, and that at least rectifies the second problem. The cursor changes just fine so long as we do a little HandDragging in between. Better, but certainly not optimal. However it should be noted, that doing the unsetCursor on the viewport doesn't work. it must absolutely be done on the graphicsview - regardless of the fact that we are setting the cursor on the viewport. To completely patch over the problem I have added these two lines after I set the cursor: graphicsview->setDragMode(QGraphicsView::ScrollHandDrag); graphicsview->setDragMode(QGraphicsView::NoDrag); Which works, but ye gads!! So something magical is happening inside these two methods that fixes the problem, but glancing at the code I don't see what. Something to do with the fact that the drag mode is changing the cursor I imagine. Just for completeness, I should also mention that the thing that triggers the mode change, is a QPushButton that has been added to the scene using QGraphicsScene->addWidget(). I don't know if that has anything to do with it, but you never know. I am hoping that either someone could clarify why I need to make these seemingly random calls. I don't think I am doing anything wrong anywhere. Thanks in advance for any help. EDIT: Here is an actual code example with the cursor patches as described above. You can look at and/or download them from the link below. It was a little long to paste here. I included the framework around which the cursors are changed, because I have a funny feeling that that is important somehow. https://gist.github.com/712654 The code where the problem lies is in MyGraphicsView.cpp starting at line 104. This is where the cursor is set in the graphics view. It is exactly as described above. Keep in mind, with the very ugly patches in place the cursors do work - more or less. Without those lines you will see very clearly the problems listed in the post above. Also included in the link, is all the code for a mainWindow that uses the view, etc... the only thing missing are the images I am using. But the images themselves don't matter, any 16x16 pngs will do.

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  • Parallel processing via multithreading in Java

    - by Robz
    There are certain algorithms whose running time can decrease significantly when one divides up a task and gets each part done in parallel. One of these algorithms is merge sort, where a list is divided into infinitesimally smaller parts and then recombined in a sorted order. I decided to do an experiment to test whether or not I could I increase the speed of this sort by using multiple threads. I am running the following functions in Java on a Quad-Core Dell with Windows Vista. One function (the control case) is simply recursive: // x is an array of N elements in random order public int[] mergeSort(int[] x) { if (x.length == 1) return x; // Dividing the array in half int[] a = new int[x.length/2]; int[] b = new int[x.length/2+((x.length%2 == 1)?1:0)]; for(int i = 0; i < x.length/2; i++) a[i] = x[i]; for(int i = 0; i < x.length/2+((x.length%2 == 1)?1:0); i++) b[i] = x[i+x.length/2]; // Sending them off to continue being divided mergeSort(a); mergeSort(b); // Recombining the two arrays int ia = 0, ib = 0, i = 0; while(ia != a.length || ib != b.length) { if (ia == a.length) { x[i] = b[ib]; ib++; } else if (ib == b.length) { x[i] = a[ia]; ia++; } else if (a[ia] < b[ib]) { x[i] = a[ia]; ia++; } else { x[i] = b[ib]; ib++; } i++; } return x; } The other is in the 'run' function of a class that extends thread, and recursively creates two new threads each time it is called: public class Merger extends Thread { int[] x; boolean finished; public Merger(int[] x) { this.x = x; } public void run() { if (x.length == 1) { finished = true; return; } // Divide the array in half int[] a = new int[x.length/2]; int[] b = new int[x.length/2+((x.length%2 == 1)?1:0)]; for(int i = 0; i < x.length/2; i++) a[i] = x[i]; for(int i = 0; i < x.length/2+((x.length%2 == 1)?1:0); i++) b[i] = x[i+x.length/2]; // Begin two threads to continue to divide the array Merger ma = new Merger(a); ma.run(); Merger mb = new Merger(b); mb.run(); // Wait for the two other threads to finish while(!ma.finished || !mb.finished) ; // Recombine the two arrays int ia = 0, ib = 0, i = 0; while(ia != a.length || ib != b.length) { if (ia == a.length) { x[i] = b[ib]; ib++; } else if (ib == b.length) { x[i] = a[ia]; ia++; } else if (a[ia] < b[ib]) { x[i] = a[ia]; ia++; } else { x[i] = b[ib]; ib++; } i++; } finished = true; } } It turns out that function that does not use multithreading actually runs faster. Why? Does the operating system and the java virtual machine not "communicate" effectively enough to place the different threads on different cores? Or am I missing something obvious?

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  • Advanced Regex: Smart auto detect and replace URLs with anchor tags

    - by Robert Koritnik
    I've written a regular expression that automatically detects URLs in free text that users enter. This is not such a simple task as it may seem at first. Jeff Atwood writes about it in his post. His regular expression works, but needs extra code after detection is done. I've managed to write a regular expression that does everything in a single go. This is how it looks like (I've broken it down into separate lines to make it more understandable what it does): 1 (?<outer>\()? 2 (?<scheme>http(?<secure>s)?://)? 3 (?<url> 4 (?(scheme) 5 (?:www\.)? 6 | 7 www\. 8 ) 9 [a-z0-9] 10 (?(outer) 11 [-a-z0-9/+&@#/%?=~_()|!:,.;cšžcd]+(?=\)) 12 | 13 [-a-z0-9/+&@#/%?=~_()|!:,.;cšžcd]+ 14 ) 15 ) 16 (?<ending>(?(outer)\))) As you may see, I'm using named capture groups (used later in Regex.Replace()) and I've also included some local characters (cšžcd), that allow our localised URLs to be parsed as well. You can easily omit them if you'd like. Anyway. Here's what it does (referring to line numbers): 1 - detects if URL starts with open braces (is contained inside braces) and stores it in "outer" named capture group 2 - checks if it starts with URL scheme also detecting whether scheme is SSL or not 3 - start parsing URL itself (will store it in "url" named capture group) 4-8 - if statement that says: if "sheme" was present then www. part is optional, otherwise mandatory for a string to be a link (so this regular expression detects all strings that start with either http or www) 9 - first character after http:// or www. should be either a letter or a number (this can be extended if you'd like to cover even more links, but I've decided not to because I can't think of a link that would start with some obscure character) 10-14 - if statement that says: if "outer" (braces) was present capture everything up to the last closing braces otherwise capture all 15 - closes the named capture group for URL 16 - if open braces were present, capture closing braces as well and store it in "ending" named capture group First and last line used to have \s* in them as well, so user could also write open braces and put a space inside before pasting link. Anyway. My code that does link replacement with actual anchor HTML elements looks exactly like this: value = Regex.Replace( value, @"(?<outer>\()?(?<scheme>http(?<secure>s)?://)?(?<url>(?(scheme)(?:www\.)?|www\.)[a-z0-9](?(outer)[-a-z0-9/+&@#/%?=~_()|!:,.;cšžcd]+(?=\))|[-a-z0-9/+&@#/%?=~_()|!:,.;cšžcd]+))(?<ending>(?(outer)\)))", "${outer}<a href=\"http${secure}://${url}\">http${secure}://${url}</a>${ending}", RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase); As you can see I'm using named capture groups to replace link with an Anchor tag: "${outer}<a href=\"http${secure}://${url}\">http${secure}://${url}</a>${ending}" I could as well omit the http(s) part in anchor display to make links look friendlier, but for now I decided not to. Question I would like my links to be replaced with shortenings as well. So when user copies a very long link (for instance if they would copy a link from google maps that usually generates long links) I would like to shorten the visible part of the anchor tag. Link would work, but visible part of an anchor tag would be shortened to some number of characters. I could as well append ellipsis at the end of at all possible (and make things even more perfect). Does Regex.Replace() method support replacement notations so that I can still use a single call? Something similar as string.Format() method does when you'd like to format values in string format (decimals, dates etc...).

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  • Organising XML results as cells in container (AS3)

    - by PJ Palomaki
    Hi, I'm having some problems figuring out how to organise data pulled off XML in cells within a container. I'm sure this should be a basic thing in AS3, but my head's fried.. can anyone help? Basically an array if fed to callThumbs() which iterates through it and compares the entries with preloaded XML _my_images. If match is found, it's sent to processXML which loads all relevant info and loads a .jpg thumbnail. All this is then fed to createCell which creates a specific cell with position values depending on x_counter and y_counter values (4 cells in a row) and adds the cell into a container _container_mc. The Problem: This all works fine and looks fine, the problem is that the cells within the container do not display in descending order. They are in random order, probably because some of the .jpg's takes longer to load etc. How do I easily organise the cells within the container in descending order by the XML .id value? Or how do I tell Flash to wait till the thumbnail and data is loaded and the cell created and added? Thanks guys, would really appreciate all the help! PJ //Flash (AS3) function callThumbs(_my_results:Array):void { // selector = 1 for specific items, 2 for search items var _thumb_url:XML; for (var r:Number=0; r < _my_results.length; r++) { // iterate through results vector, compare with _my_images XML .id for (var i:Number=0; i < _my_images.length(); i++) { if (_my_images[i][email protected]() == _my_results[r]) { _thumb_url=_my_images[i]; processXML(_thumb_url, i); } } } } // End callThumbs function processXML(imageXML:XML, num:Number) { // Processes XML data and loads .jpg thumbnail var _thumb_loader=new Loader(); _thumb_loader.load(new URLRequest("thumbs/thumb_sm/" + imageXML.@id + "_st.jpg")); _thumb_loader.contentLoaderInfo.addEventListener(Event.COMPLETE,thumbLoaded); _thumb_loader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, urlNotFound); var id:XMLList = new XMLList; id = imageXML.@id; var description:XMLList = new XMLList; description = imageXML.@description; function urlNotFound(event:IOErrorEvent):void { trace("The image URL '" + String(imageXML.@id) + "' was not found."); } function thumbLoaded(e:Event):void { var imageLoader:Loader = Loader(e.target.loader); var bm:Bitmap = Bitmap(imageLoader.content); createCell(bm, id, description, num); adjustFooterBar(); // Adjust bottom footer } } // End processXML private function createCell(_image:Bitmap, _id, _description:String, _position):void { // Creates a cell with data, add to container var _cell_mc = new CellTitle(); _cell_mc.initCell(_image, _id, _description, _position, x_counter, y_counter); if (x_counter+1 < 4) { x_counter++; } else { x_counter = 0; y_counter++; } _container_mc.addChild(_cell_mc); // movieclip container } // End createCell

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  • Decentralized synchronized secure data storage

    - by Alberich
    Introduction Hi, I am going to ask a question which seems utopic for me, but I need to know if there is a way to achieve what I need. And if not, I need to know why not. The idea Suppose I have a database structure, in MySql. I want to create some solution to allow anyone (no matter who, no matter where) to have a synchronized copy (updated clone) of this database (with its content) Well, and it is not going to be just one synchronized copy, it could (and should) be a multiple replication (supposing the basic, this means, for example, ten copies all over the world) And, the most important thing: It must be secure. By secure I mean only real-accepted transactions will be synchronized with all the others (no matter how many) database copies/clones. Note: Since it would be quite difficult to make the synchronization in real-time, I will design everything to make this feature dispensable. So it is not required. My auto-suggestion This is how I am thinking to manage it: Time identifiers and Updates checking: Every action (insert, update, delete...) will be stored as the action instruction itself, associated to the time identifier. [I think better than a DATETIME field, it'll be an INT one, with the number of miliseconds passed from 1st january 2013 on, for example]. So each copy is going to ask to the "neighbour copy" for new actions done since last update, and execute them after checking they are allowed. Problem 1: the "neighbour copy" could be outdated too. Solution 1: do not ask just one neighbour, create a random list with some of the copies/clones and ask them for news (I could avoid the list and ask ALL the clones for updates, but this will be inefficient if clones number ascends too much). Problem 2: Real-time global synchronization is not active. What if... Someone at CLONE_ENTERPRISING inserts a row into TABLE. ... this row goes to every clone ... Someone at CLONE_FIXEMALL deletes this row. ... and at the same time, somewhere in an outdated clone ... Someone at CLONE_DROPOUT edits this row (now inexistent at the other clones) Solution 2: easy stuff, force a GLOBAL synchronization before doing any new "depending-on-third-data action" (edit, for example). This global synch. will be unnecessary when making an INSERT, for instance. Note: Well, someone could have some fun, and make the same insert in two clones... since they're not getting updated in real-time, this row will exist twice. But, it's the same as when we have one single database, in some needed cases we check if there is an existing same-row before doing the final action. Not a problem. Problem 3: It is possible to edit the code and do not filter actions, so someone could spread instructions to delete everything, or just make some trolling activity. This is not a problem, since good clones will always be somewhere. Those who got bad won't interest anymore. I really appreciate if you read. I know this is not the perfect solution, it has possibly hundred of holes, but it is my basic start. I will now appreciate anything you can teach me now. Thanks a lot. PS.: It could be that all this I am trying already exists and has its own name. Sorry for asking then (I'd anyway thank this name, if it exists)

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  • Recommended integration mechanism for bi-directional, authenticated, encrypted connection in C clien

    - by rcampbell
    Let me first give an example. Imagine you have a single server running a JVM application. This server keeps a collection of N equations, once for each client: Client #1: 2x Client #2: 1 + y Client #3: z/4 This server includes an HTTP interface so that random visitors can type https://www.acme.com/client/3 int their browsers and see the latest evaluated result of z/4. The tricky part is that either the client or the server may change the variable value at any time, informing the other party immediately. More specifically, Client #3 - a C app - can initially tell the server that z = 20. An hour later that same client informs the server that z = 23. Likewise the server can later inform the client that z = 28. As caf pointed out in the comments, there can be a race condition when values are changed by the client and server simultaneously. The solution would be for both client and server to send the operation performed in their message, which would need to be executed by the other party. To keep things simple, let's limit the operations to (commutative) addition, allowing us to disregard message ordering. For example, the client seeds the server with z = 20: server:z=20, client:z=20 server sends {+3} message (so z=23 locally) & client sends {-2} message (so z=18 locally) at the exact same time server receives {-2} message at some point, adds to his local copy so z=21 client receives {+3} message at some point, adds to his local copy so z=21 As long as all messages are eventually evaluated by both parties, the correct answer will eventually be given to the users of the client and server since we limited ourselves to commutative operations (addition of 3 and -2). This does mean that both client and server can be returning incorrect answers in the time it takes for messages to be exchanged and processed. While undesirable, I believe this is unavoidable. Some possible implementations of this idea include: Open an encrypted, always on TCP socket connection for communication Pros: no additional infrastructure needed, client and server know immediately if there is a problem (disconnect) with the other party, fairly straightforward (except the the encryption), native support from both JVM and C platforms Cons: pretty low-level so you end up writing a lot yourself (protocol, delivery verification, retry-on-failure logic), probably have a lot of firewall headaches during client app installation Asynchronous messaging (ex: ActiveMQ) Pros: transactional, both C & Java integration, free up the client and server apps from needing retry logic or delivery verification, pretty straightforward encryption, easy extensibility via message filters/routers/etc Cons: need additional infrastructure (message server) which must never fail, Database or file system as asynchronous integration point Same pros/cons as above but messier RESTful Web Service Pros: simple, possible reuse of the server's existing REST API, SSL figures out the encryption problem for you (maybe use RSA key a la GitHub for authentication?) Cons: Client now needs to run a C HTTP REST server w/SSL, client and server need retry logic. Axis2 has both a Java and C version, but you may be limited to SOAP. What other techniques should I be evaluating? What real world experiences have you had with these mechanisms? Which do you recommend for this problem and why?

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  • How to bind to the sum of two data bound values in WPF?

    - by Sheridan
    I have designed an analog clock control. It uses the stroke from two ellipses to represent an outer border and an inner border to the clock face. I have exposed properties in the UserControl that allow a user to alter the thickness of these two borders. The Ellipse.StrokeThickness properties are then bound to these UserControl properties. At the moment, I am binding the UserControl property for the outer border thickness to the margins of the inner elements so that they are not hidden when the border size is increased. <Ellipse Name="OuterBorder" Panel.ZIndex="1" StrokeThickness="{Binding OuterBorderThickness, ElementName=This}" Stroke="{StaticResource OuterBorderBrush}" /> <Ellipse Name="InnerBorder" Panel.ZIndex="5" StrokeThickness="{Binding InnerBorderThickness, ElementName=This}" Margin="{Binding OuterBorderThickness, ElementName=This}" Stroke="{StaticResource InnerBorderBrush}"> ... <Ellipse Name="Face" Panel.ZIndex="1" Margin="{Binding OuterBorderThickness, ElementName=This}" Fill="{StaticResource FaceBackgroundBrush}" /> ... The problem is that if the inner border thickness is increased, this does not affect the margins and so the hour ticks and numbers can become partially obscured or hidden. So what I really need is to be able to bind the margin properties of the inner controls to the sum of the inner and outer border thickness values (they are of type double). I have done this successfully using 'DataContext = this;', but am trying to rewrite the control without this as I hear it is not recommended. I also thought about using a converter and passing the second value as the ConverterParameter, but didn't know how to bind to the ConverterParameter. Any tips would be greatly appreciated. EDIT Thanks to Kent's suggestion, I've created a simple MultiConverter to add the input values and return the result. I've hooked the SAME multibinding with converter XAML to both a TextBlock.Text property and the TextBlock.Margin property to test it. <TextBlock> <TextBlock.Text> <MultiBinding Converter="{StaticResource SumConverter}" ConverterParameter="Add"> <Binding Path="OuterBorderThickness" ElementName="This" /> <Binding Path="InnerBorderThickness" ElementName="This" /> </MultiBinding> </TextBlock.Text> <TextBlock.Margin> <MultiBinding Converter="{StaticResource SumConverter}" ConverterParameter="Add"> <Binding Path="OuterBorderThickness" ElementName="This" /> <Binding Path="InnerBorderThickness" ElementName="This" /> </MultiBinding> </TextBlock.Margin> </TextBlock> I can see the correct value displayed in the TexBlock, but the Margin is not set. Any ideas? EDIT Interestingly, the Margin property can be bound to a data property of type double, but this does not seem to apply within a MultiBinding. As advised by Kent, I changed the Converter to return the value as a Thickness object and now it works. Thanks Kent.

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  • Cannot decode complete cipher list in .NET SslStream handshake.

    - by karmasponge
    While attempting to move from a 'C' based SSL implementation to C# using the .NET SslStream and we have run into what look like cipher compatibility issues with the .NET SslStream and a AS400 machine we are trying to connect to (which worked previously). When we call SslStream.AuthenticateAsClient it is sending the following: 16 03 00 00 37 01 00 00 33 03 00 4d 2c 00 ee 99 4e 0c 5d 83 14 77 78 5c 0f d3 8f 8b d5 e6 b8 cd 61 0f 29 08 ab 75 03 f7 fa 7d 70 00 00 0c 00 05 00 0a 00 13 00 04 00 02 00 ff 01 00 Which decodes as (based on http://www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt) [16] Record Type [03 00] SSL Version [00 37] Body length [01] SSL3_MT_CLIENT_HELLO [00 00 33] Length (51 bytes) [03 00] Version number = 768 [4d 2c 00 ee] 4 Bytes unix time [… ] 28 Bytes random number [00] Session number [00 0c] 12 bytes (2 * 6 Cyphers)? [00 05, 00 0a, 00 13, 00 04, 00 02, 00 ff] - [RC4, PBE-MD5-DES, RSA, MD5, PKCS, ???] [01 00] Null compression method The as400 server responds back with: 15 03 00 00 02 02 28 [15] SSL3_RT_ALERT [03 00] SSL Version [00 02] Body Length (2 Bytes) [02 28] 2 = SSL3_RT_FATAL, 40 = SSL3_AD_HANDSHAKE_FAILURE I'm specifically looking to decode the '00 FF' at the end of the cyphers. Have I decoded it correctly? What does, if anything, '00 FF' decode too? I am using the following code to test/reproduce: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Net.Sockets; using System.Net.Security; using System.Security.Authentication; using System.IO; using System.Diagnostics; using System.Security.Cryptography.X509Certificates; namespace TestSslStreamApp { class DebugStream : Stream { private Stream AggregatedStream { get; set; } public DebugStream(Stream stream) { AggregatedStream = stream; } public override bool CanRead { get { return AggregatedStream.CanRead; } } public override bool CanSeek { get { return AggregatedStream.CanSeek; } } public override bool CanWrite { get { return AggregatedStream.CanWrite; } } public override void Flush() { AggregatedStream.Flush(); } public override long Length { get { return AggregatedStream.Length; } } public override long Position { get { return AggregatedStream.Position; } set { AggregatedStream.Position = value; } } public override int Read(byte[] buffer, int offset, int count) { int bytesRead = AggregatedStream.Read(buffer, offset, count); return bytesRead; } public override long Seek(long offset, SeekOrigin origin) { return AggregatedStream.Seek(offset, origin); } public override void SetLength(long value) { AggregatedStream.SetLength(value); } public override void Write(byte[] buffer, int offset, int count) { AggregatedStream.Write(buffer, offset, count); } } class Program { static void Main(string[] args) { const string HostName = "as400"; TcpClient tcpClient = new TcpClient(HostName, 992); SslStream sslStream = new SslStream(new DebugStream(tcpClient.GetStream()), false, null, null, EncryptionPolicy.AllowNoEncryption); sslStream.AuthenticateAsClient(HostName, null, SslProtocols.Ssl3, false); } } }

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  • jQuery - I'm getting unexpected outputs from a basic math formula.

    - by OllieMcCarthy
    Hi I would like to start by saying I'd greatly appreciate anyones help on this. I have built a small caculator to calculate the amount a consumer can save annually on energy by installing a ground heat pump or solar panels. As far as I can tell the mathematical formulas are correct and my client verified this yesterday when I showed him the code. Two problems. The first is that the calculator is outputting ridiculously large numbers for the first result. The second problem is that the solar result is only working when there are no zeros in the fields. Are there some quirks as to how one would write mathematical formulas in JS or jQuery? Any help greatly appreciated. Here is the link - http://www.olliemccarthy.com/test/johncmurphy/?page_id=249 And here is the code for the entire function - $jq(document).ready(function(){ // Energy Bill Saver // Declare Variables var A = ""; // Input for Oil var B = ""; // Input for Storage Heater var C = ""; // Input for Natural Gas var D = ""; // Input for LPG var E = ""; // Input for Coal var F = ""; // Input for Wood Pellets var G = ""; // Input for Number of Occupants var J = ""; var K = ""; var H = ""; var I = ""; // Declare Constants var a = "0.0816"; // Rate for Oil var b = "0.0963"; // Rate for NightRate var c = "0.0558"; // Rate for Gas var d = "0.1579"; // Rate for LPG var e = "0.121"; // Rate for Coal var f = "0.0828"; // Rate for Pellets var g = "0.02675"; // Rate for Heat Pump var x = "1226.4"; // Splittin up I to avoid error var S1 = ""; // Splitting up the calcuation for I var S2 = ""; // Splitting up the calcuation for I var S3 = ""; // Splitting up the calcuation for I var S4 = ""; // Splitting up the calcuation for I var S5 = ""; // Splitting up the calcuation for I var S6 = ""; // Splitting up the calcuation for I // Calculate H (Ground Sourced Heat Pump) $jq(".es-calculate").click(function(){ $jq(".es-result-wrap").slideDown(300); A = $jq("input.es-oil").val(); B = $jq("input.es-storage").val(); C = $jq("input.es-gas").val(); D = $jq("input.es-lpg").val(); E = $jq("input.es-coal").val(); F = $jq("input.es-pellets").val(); G = $jq("input.es-occupants").val(); J = ( A / a ) + ( B / b ) + ( C / c ) + ( D / d ) + ( E / e ) + ( F / f ) ; H = A + B + C + D + E + F - ( J * g ) ; K = ( G * x ) ; if ( A !== "0" ) { S1 = ( ( ( A / a ) / J ) * K * a ) ; } else { S1 = "0" ; } if ( B !== "0" ) { S2 = ( ( ( B / b ) / J ) * K * b ) ; } else { S2 = "0" ; } if ( C !== "0" ) { S3 = ( ( ( C / c ) / J ) * K * c ) ; } else { S3 = "0" ; } if ( D !== "0" ) { S4 = ( ( ( D / d ) / J ) * K * d ) ; } else { S4 = "0" ; } if ( E !== "0" ) { S5 = ( ( ( E / e ) / J ) * K * e ) ; } else { S5 = "0" ; } if ( F !== "0" ) { S6 = ( ( ( F / f ) / J ) * K * f ) ; } else { S6 = "0" ; } I = S1 + S2 + S3 + S4 + S5 + S6 ; if(!isNaN(H)) {$jq("span.es-result-span-h").text(H.toFixed(2));} else{$jq("span.es-result-span-h").text('Error: Please enter numerals only');} if(!isNaN(I)) {$jq("span.es-result-span-i").text(I.toFixed(2));} else{$jq("span.es-result-span-i").text('Error: Please enter numerals only');} }); });

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  • Do you have suggestions for these assembly mnemonics?

    - by Noctis Skytower
    Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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  • Why does this Quicksort work?

    - by IVlad
    I find this Quicksort partitioning approach confusing and wrong, yet it seems to work. I am referring to this pseudocode. Note: they also have a C implementation at the end of the article, but it's very different from their pseudocode, so I don't care about that. I have also written it in C like this, trying to stay true to the pseudocode as much as possible, even if that means doing some weird C stuff: #include <stdio.h> int partition(int a[], int p, int r) { int x = a[p]; int i = p - 1; int j = r + 1; while (1) { do j = j - 1; while (!(a[j] <= x)); do i = i + 1; while (!(a[i] >= x)); if (i < j) { int t = a[i]; a[i] = a[j]; a[j] = t; } else { for (i = 1; i <= a[0]; ++i) printf("%d ", a[i]); printf("- %d\n", j); return j; } } } int main() { int a[100] = //{8, 6,10,13,15,8,3,2,12}; {7, 7, 6, 2, 3, 8, 4, 1}; partition(a, 1, a[0]); return 0; } If you run this, you'll get the following output: 1 6 2 3 4 8 7 - 5 However, this is wrong, isn't it? Clearly a[5] does not have all the values before it lower than it, since a[2] = 6 > a[5] = 4. Not to mention that 7 is supposed to be the pivot (the initial a[p]) and yet its position is both incorrect and lost. The following partition algorithm is taken from wikipedia: int partition2(int a[], int p, int r) { int x = a[r]; int store = p; for (int i = p; i < r; ++i) { if (a[i] <= x) { int t = a[i]; a[i] = a[store]; a[store] = t; ++store; } } int t = a[r]; a[r] = a[store]; a[store] = t; for (int i = 1; i <= a[0]; ++i) printf("%d ", a[i]); printf("- %d\n", store); return store; } And produces this output: 1 6 2 3 8 4 7 - 1 Which is a correct result in my opinion: the pivot (a[r] = a[7]) has reached its final position. However, if I use the initial partitioning function in the following algorithm: void Quicksort(int a[], int p, int r) { if (p < r) { int q = partition(a, p, r); // initial partitioning function Quicksort(a, p, q); Quicksort(a, q + 1, r); // I'm pretty sure q + r was a typo, it doesn't work with q + r. } } ... it seems to be a correct sorting algorithm. I tested it out on a lot of random inputs, including all 0-1 arrays of length 20. I have also tried using this partition function for a selection algorithm, in which it failed to produce correct results. It seems to work and it's even very fast as part of the quicksort algorithm however. So my questions are: Can anyone post an example on which the algorithm DOESN'T work? If not, why does it work, since the partitioning part seems to be wrong? Is this another partitioning approach that I don't know about?

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  • How to implement dynamic binary search for search and insert operations of n element (C or C++)

    - by iecut
    The idea is to use multiple arrays, each of length 2^k, to store n elements, according to binary representation of n.Each array is sorted and different arrays are not ordered in any way. In the above mentioned data structure, SEARCH is carried out by a sequence of binary search on each array. INSERT is carried out by a sequence of merge of arrays of the same length until an empty array is reached. More Detail: Lets suppose we have a vertical array of length 2^k and to each node of that array there attached horizontal array of length 2^k. That is, to the first node of vertical array, a horizontal array of length 2^0=1 is connected,to the second node of vertical array, a horizontal array of length 2^1= 2 is connected and so on. So the insert is first carried out in the first horizontal array, for the second insert the first array becomes empty and second horizontal array is full with 2 elements, for the third insert 1st and 2nd array horiz. array are filled and so on. I implemented the normal binary search for search and insert as follows: int main() { int a[20]= {0}; int n, i, j, temp; int *beg, *end, *mid, target; printf(" enter the total integers you want to enter (make it less then 20):\n"); scanf("%d", &n); if (n = 20) return 0; printf(" enter the integer array elements:\n" ); for(i = 0; i < n; i++) { scanf("%d", &a[i]); } // sort the loaded array, binary search! for(i = 0; i < n-1; i++) { for(j = 0; j < n-i-1; j++) { if (a[j+1] < a[j]) { temp = a[j]; a[j] = a[j+1]; a[j+1] = temp; } } } printf(" the sorted numbers are:"); for(i = 0; i < n; i++) { printf("%d ", a[i]); } // point to beginning and end of the array beg = &a[0]; end = &a[n]; // use n = one element past the loaded array! // mid should point somewhere in the middle of these addresses mid = beg += n/2; printf("\n enter the number to be searched:"); scanf("%d",&target); // binary search, there is an AND in the middle of while()!!! while((beg <= end) && (*mid != target)) { // is the target in lower or upper half? if (target < *mid) { end = mid - 1; // new end n = n/2; mid = beg += n/2; // new middle } else { beg = mid + 1; // new beginning n = n/2; mid = beg += n/2; // new middle } } // find the target? if (*mid == target) { printf("\n %d found!", target); } else { printf("\n %d not found!", target); } getchar(); // trap enter getchar(); // wait return 0; } Could anyone please suggest how to modify this program or a new program to implement dynamic binary search that works as explained above!!

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  • AES encryption/decryption java bouncy castle explanation?

    - by Programmer0
    Can someone please explain what this program is doing pointing out some of the major points? I'm looking at the code and I'm completely lost. I just need explanation on the encryption/decryption phases. I think it generates an AES 192 key at one point but I'm not 100% sure. I'm not sure what the byte/ivBytes are used for either. import java.security.Key; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.spec.IvParameterSpec; public class RandomKey { public static void main(String[] args) throws Exception { byte[] input = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07 }; byte[] ivBytes = new byte[] { 0x00, 0x00, 0x00, 0x01, 0x04, 0x05, 0x06, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 }; //initializing a new initialization vector IvParameterSpec ivSpec = new IvParameterSpec(ivBytes); //what does this actually do? Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding", "BC"); //what does this do? KeyGenerator generator = KeyGenerator.getInstance("AES","BC"); //I assume this generates a key size of 192 bits generator.init(192); //does this generate a random key? Key encryptKey = generator.generateKey(); System.out.println("input: " +toHex(input)); //encryption phase cipher.init(Cipher.ENCRYPT_MODE, encryptKey, ivSpec); //what is this doing? byte[] cipherText = new byte[cipher.getOutputSize(input.length)]; //what is this doing? int ctLength = cipher.update(input, 0, input.length, cipherText,0); //getting the cipher text length i assume? ctLength += cipher.doFinal (cipherText, ctLength ); System.out.println ("Cipher: " +toHex(cipherText) + " bytes: " + ctLength); //decryption phase cipher.init(Cipher.DECRYPT_MODE, encryptKey, ivSpec); //storing the ciphertext in plaintext i'm assuming? byte[] plainText = new byte[cipher.getOutputSize(ctLength)]; int ptLength = cipher.update(cipherText, 0, ctLength, plainText, 0); //getting plaintextLength i think? ptLength= cipher.doFinal (plainText, ptLength); System.out.println("plain: " + toHex(plainText, ptLength)); } private static String digits = "0123456789abcdef"; public static String toHex(byte[] data, int length) { StringBuffer buf = new StringBuffer(); for (int i=0; i!= length; i++) { int v = data[i] & 0xff; buf.append(digits.charAt(v >>4)); buf.append(digits.charAt(v & 0xf)); } return buf.toString(); } public static String toHex(byte[] data) { return toHex(data, data.length); } }

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  • Getting Segmentation Fault in C++, but why?

    - by Carlos
    I am getting segmentation fault in this code but i cant figure out why. I know a segmentation fault happens when a pointer is NULL, or when it points to a random memory address. #include <iostream> #include <fstream> #include <cmath> using namespace std; //**************************** CLASS ******************************* class Database { struct data{ string city; float latitude, longitude; data *link; }*p; public: Database(); void display(); void add(string cityName, float lat, float lon); private: string cityName; float lat, lon; }; //************************** CLASS METHODS ************************** Database::Database() { p = NULL; } void Database::add(string cityName, float lat, float lon){ data *q, *t; if(p == NULL){ p = new data; p -> city = cityName; p -> latitude = lat; p -> longitude = lon; p -> link = NULL; } else{ q = p; while(q -> link != NULL){ q = q -> link; } t = new data; t -> city = cityName; t -> latitude = lat; t -> longitude = lon; q -> link = t; } } void Database::display() { data *q; cout<<endl; for( q = p ; q != NULL ; q = q->link ) cout << endl << q -> city; } //***************************** MAIN ******************************* //*** INITIALIZATION *** Database D; void loadDatabase(); //****** VARIABLES ***** //******* PROGRAM ****** int main() { loadDatabase(); D.display(); } void loadDatabase() { int i = 0; string cityName; float lat, lon; fstream city; city.open("city.txt", ios::in); fstream latitude; latitude.open("lat.txt", ios::in); fstream longitude; longitude.open("lon.txt", ios::in); while(!city.eof()){ //************************************ city >> cityName; //* * latitude >> lat; //Here is where i think is the problem longitude >> lon; //* * D.add(cityName, lat, lon); //************************************ } city.close(); latitude.close(); longitude.close(); } This is the error am actually getting in console

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  • BB Code Parser (in formatting phase) with jQuery jammed due to messed up loops most likely

    - by Oskar
    Greetings everyone, I'm making a BB Code Parser but I'm stuck on the JavaScript front. I'm using jQuery and the caret library for noting selections in a text field. When someone selects a piece of text a div with formatting options will appear. I have two issues. Issue 1. How can I make this work for multiple textfields? I'm drawing a blank as it currently will detect the textfield correctly until it enters the $("#BBtoolBox a").mousedown(function() { } loop. After entering it will start listing one field after another in a random pattern in my eyes. !!! MAIN Issue 2. I'm guessing this is the main reason for issue 1 as well. When I press a formatting option it will work on the first action but not the ones afterwards. It keeps duplicating the variable parsed. (if I only keep to one field it will never print in the second) Issue 3 If you find anything especially ugly in the code, please tell me how to improve myself. I appriciate all help I can get. Thanks in advance $(document).ready(function() { BBCP(); }); function BBCP(el) { if(!el) { el = "textarea"; } // Stores the cursor position of selection start $(el).mousedown(function(e) { coordX = e.pageX; coordY = e.pageY; // Event of selection finish by using keyboard }).keyup(function() { BBtoolBox(this, coordX, coordY); // Event of selection finish by using mouse }).mouseup(function() { BBtoolBox(this, coordX, coordY); // Event of field unfocus }).blur(function() { $("#BBtoolBox").hide(); }); } function BBtoolBox(el, coordX, coordY) { // Variable containing the selected text by Caret selection = $(el).caret().text; // Ignore the request if no text is selected if(selection.length == 0) { $("#BBtoolBox").hide(); return; } // Print the toolbox if(!document.getElementById("BBtoolBox")) { $(el).before("<div id=\"BBtoolBox\" style=\"left: "+ ( coordX + 5 ) +"px; top: "+ ( coordY - 30 ) +"px;\"></div>"); // List of actions $("#BBtoolBox").append("<a href=\"#\" onclick=\"return false\"><img src=\"./icons/text_bold.png\" alt=\"B\" title=\"Bold\" /></a>"); $("#BBtoolBox").append("<a href=\"#\" onclick=\"return false\"><img src=\"./icons/text_italic.png\" alt=\"I\" title=\"Italic\" /></a>"); } else { $("#BBtoolBox").css({'left': (coordX + 3) +'px', 'top': (coordY - 30) +'px'}).show(); } // Parse the text according to the action requsted $("#BBtoolBox a").mousedown(function() { switch($(this).children(":first").attr("alt")) { case "B": // bold parsed = "[b]"+ selection +"[/b]"; break; case "I": // italic parsed = "[i]"+ selection +"[/i]"; break; } // Changes the field value by replacing the selection with the variable parsed $(el).val($(el).caret().replace(parsed)); $("#BBtoolBox").hide(); return false; }); }

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  • More localized, efficient Lowest Common Ancestor algorithm given multiple binary trees?

    - by mstksg
    I have multiple binary trees stored as an array. In each slot is either nil (or null; pick your language) or a fixed tuple storing two numbers: the indices of the two "children". No node will have only one child -- it's either none or two. Think of each slot as a binary node that only stores pointers to its children, and no inherent value. Take this system of binary trees: 0 1 / \ / \ 2 3 4 5 / \ / \ 6 7 8 9 / \ 10 11 The associated array would be: 0 1 2 3 4 5 6 7 8 9 10 11 [ [2,3] , [4,5] , [6,7] , nil , nil , [8,9] , nil , [10,11] , nil , nil , nil , nil ] I've already written simple functions to find direct parents of nodes (simply by searching from the front until there is a node that contains the child) Furthermore, let us say that at relevant times, both all trees are anywhere between a few to a few thousand levels deep. I'd like to find a function P(m,n) to find the lowest common ancestor of m and n -- to put more formally, the LCA is defined as the "lowest", or deepest node in which have m and n as descendants (children, or children of children, etc.). If there is none, a nil would be a valid return. Some examples, given our given tree: P( 6,11) # => 2 P( 3,10) # => 0 P( 8, 6) # => nil P( 2,11) # => 2 The main method I've been able to find is one that uses an Euler trace, which turns the given tree, with a node A to be the invisible parent of 0 and 1 with a depth of -1, into: A-0-2-6-2-7-10-7-11-7-2-0-3-0-A-1-4-1-5-8-5-9-5-1-A And from that, simply find the node between your given m and n that has the lowest number; For example, to find P(6,11), look for a 6 and an 11 on the trace. The number between them that is the lowest is 2, and that's your answer. If A is in between them, return nil. -- Calculating P(6,11) -- A-0-2-6-2-7-10-7-11-7-2-0-3-0-A-1-4-1-5-8-5-9-5-1-A ^ ^ ^ | | | m lowest n Unfortunately, I do believe that finding the Euler trace of a tree that can be several thousands of levels deep is a bit machine-taxing...and because my tree is constantly being changed throughout the course of the programming, every time I wanted to find the LCA, I'd have to re-calculate the Euler trace and hold it in memory every time. Is there a more memory efficient way, given the framework I'm using? One that maybe iterates upwards? One way I could think of would be the "count" the generation/depth of both nodes, and climb the lowest node until it matched the depth of the highest, and increment both until they find someone similar. But that'd involve climbing up from level, say, 3025, back to 0, twice, to count the generation, and using a terribly inefficient climbing-up algorithm in the first place, and then re-climbing back up. Are there any other better ways?

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