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  • conditional update records mysql query

    - by Shakti Singh
    Hi, Is there any single msql query which can update customer DOB? I want to update the DOB of those customers which have DOB greater than current date. example:- if a customer have dob 2034 update it to 1934 , if have 2068 updated with 1968. There was a bug in my system if you enter date less than 1970 it was storing it as 2070. The bug is solved now but what about the customers which have wrong DOB. So I have to update their DOB. All customers are stored in customer_entity table and the entity_id is the customer_id Details is as follows:- desc customer_entity -> ; +------------------+----------------------+------+-----+---------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +------------------+----------------------+------+-----+---------------------+----------------+ | entity_id | int(10) unsigned | NO | PRI | NULL | auto_increment | | entity_type_id | smallint(8) unsigned | NO | MUL | 0 | | | attribute_set_id | smallint(5) unsigned | NO | | 0 | | | website_id | smallint(5) unsigned | YES | MUL | NULL | | | email | varchar(255) | NO | MUL | | | | group_id | smallint(3) unsigned | NO | | 0 | | | increment_id | varchar(50) | NO | | | | | store_id | smallint(5) unsigned | YES | MUL | 0 | | | created_at | datetime | NO | | 0000-00-00 00:00:00 | | | updated_at | datetime | NO | | 0000-00-00 00:00:00 | | | is_active | tinyint(1) unsigned | NO | | 1 | | +------------------+----------------------+------+-----+---------------------+----------------+ 11 rows in set (0.00 sec) And the DOB is stored in the customer_entity_datetime table the column value contain the DOB. but in this table values of all other attribute are also stored such as fname,lname etc. So the attribute_id with value 11 is DOB attribute. mysql> desc customer_entity_datetime; +----------------+----------------------+------+-----+---------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------------+----------------------+------+-----+---------------------+----------------+ | value_id | int(11) | NO | PRI | NULL | auto_increment | | entity_type_id | smallint(8) unsigned | NO | MUL | 0 | | | attribute_id | smallint(5) unsigned | NO | MUL | 0 | | | entity_id | int(10) unsigned | NO | MUL | 0 | | | value | datetime | NO | | 0000-00-00 00:00:00 | | +----------------+----------------------+------+-----+---------------------+----------------+ 5 rows in set (0.01 sec) Thanks.

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  • Jquery CheckBox Selection/Deselection optimally given X checkboxes

    - by Amitd
    Hi guys, I have suppose say 'X' check-boxes(any input elements) in a Form and "M" option selection indexes ("M" less than equal to "X"). then how do i select the "M" option indexes/values and deselect the rest of check-boxes optimally? i.e.Suppose I have 10 Checkboxes and 5 Option Indices(eg: 1,2,4,5,8) then i have to select checkboxes with given index . I could come up with the following code: HTML: <div id="Options"> <input id="choice_1" type="checkbox" name="choice_1" value="Option1"><label for="choice_1">Option1</label> <input id="choice_2" type="checkbox" name="choice_2" value="Option2"><label for="choice_2">Option2</label> <input id="choice_3" type="checkbox" name="choice_3" value="Option3"><label for="choice_3">Option3</label> .. ..till choice_10 </div> IN JS: //Have to select checkboxes with "Value" in choicesToSelect and give a selection //effect to its label var choicesToSelect={"Option1","Option9","Option3","Option4","Option2"}; selectHighlightCheckBoxes(choicesToSelect); function selectHighlightCheckBoxes(choices){ $.each( choices, function(intIndex, objValue) { //select based on id or value or some criteria var option = $("#Options :input[value=" + objValue + "]") ; if ($(option).is("input[type='radio']") || $(option).is("input[type='checkbox']")) { $(option).attr('checked', true); $(option).next('label:first').css({ 'border': '1px solid #FF0000', 'background-color': '#BEF781', 'font-weight': 'bolder' }); } else if ($(option).is("input[type='text']")) { $(option).css({ 'border': '1px solid #FF0000', 'background-color': '#BEF781', 'font-weight': 'bolder' }); } else { } } ); } But i want to also add effect to the rest (not in choicesToSelect array) also. (may be red color to those not in choiceToSelect) Can this be done in the one traversal/loop? Optimally? or Better way?

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  • Memory Bandwidth Performance for Modern Machines

    - by porgarmingduod
    I'm designing a real-time system that occasionally has to duplicate a large amount of memory. The memory consists of non-tiny regions, so I expect the copying performance will be fairly close to the maximum bandwidth the relevant components (CPU, RAM, MB) can do. This led me to wonder what kind of raw memory bandwidth modern commodity machine can muster? My aging Core2Duo gives me 1.5 GB/s if I use 1 thread to memcpy() (and understandably less if I memcpy() with both cores simultaneously.) While 1.5 GB is a fair amount of data, the real-time application I'm working on will have have something like 1/50th of a second, which means 30 MB. Basically, almost nothing. And perhaps worst of all, as I add multiple cores, I can process a lot more data without any increased performance for the needed duplication step. But a low-end Core2Due isn't exactly hot stuff these days. Are there any sites with information, such as actual benchmarks, on raw memory bandwidth on current and near-future hardware? Furthermore, for duplicating large amounts of data in memory, are there any shortcuts, or is memcpy() as good as it will get? Given a bunch of cores with nothing to do but duplicate as much memory as possible in a short amount of time, what's the best I can do?

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  • Javascript doesnt update

    - by Trikam
    Hi all, I have a function that passes a parameter which is a function call and then i use setTimeout to call this passed function call. now i tried two methods with setTimout to raise the event and i used function.call(). When this passed parameter function call was raised none of the javascript was being updated, below is the javascript which im using to raise the event and the javascript which is supposed to be updated: The function being passed is [context] - function() { ErrorMessageFileSelect('diverrortextchoosechannal','The file chosen is to big, you must choose a file less than 1MB'); } function FileSizeOnLoad(contentLength,context) { if (context != null) { // context.call(); setTimeout(context,0); // or context.call(); } else { $('#inputHiddenFileSizeField').val(contentLength); DisplayChoseFileInformation(contentLength); } } //this is where the update should happen function ErrorMessageFileSelect(className, errorMessage) { $('div.' + className).text(errorMessage); alert($('div.' + className).text()); } Is there somthing im missing, can someone help me with this issue please. Thanks

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  • Can ElementTree be told to preserve the order of attributes?

    - by dmckee
    I've written a fairly simple filter in python using ElementTree to munge the contexts of some xml files. And it works, more or less. But it reorders the attributes of various tags, and I'd like it to not do that. Does anyone know a switch I can throw to make it keep them in specified order? Context for this I'm working with and on a particle physics tool that has a complex, but oddly limited configuration system based on xml files. Among the many things setup that way are the paths to various static data files. These paths are hardcoded into the existing xml and there are no facilities for setting or varying them based on environment variables, and in our local installation they are necessarily in a different place. This isn't a disaster because the combined source- and build-control tool we're using allows us to shadow certain files with local copies. But even thought the data fields are static the xml isn't, so I've written a script for fixing the paths, but with the attribute rearrangement diffs between the local and master versions are harder to read than necessary. This is my first time taking ElementTree for a spin (and only my fifth or sixth python project) so maybe I'm just doing it wrong. Abstracted for simplicity the code looks like this: tree = elementtree.ElementTree.parse(inputfile) i = tree.getiterator() for e in i: e.text = filter(e.text) tree.write(outputfile) Reasonable or dumb? Related links: How can I get the order of an element attribute list using Python xml.sax? Preserve order of attributes when modifying with minidom

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  • How Can I: Generate 40/64 Bit WEP Key In Python?

    - by Aktariel
    So, I've been beating my head against the wall of this issue for several months now, partly because it's a side interest and partly because I suck at programming. I've searched and researched all across the web, but have not had any luck (except one small bit of success; see below), so I thought I might try asking the experts. What I am trying to do is, as the title suggests, generate a 40/64 bit WEP key from a passphrase, according to the "de facto" standard. (A site such as [http://www.powerdog.com/wepkey.cgi] produces the expected outputs.) I have already written portions of the script that take inputs and write them to a file; one of the inputs would be the passphrase, sanitized to lower case. For the longest time I had no idea what the defacto standard was, much less how to even go about implementing it. I finally stumbled across a paper (http://www.lava.net/~newsham/wlan/WEP_password_cracker.pdf) that sheds as much light as I've had yet on the issue (page 18 has the relevant bits). Apparently, the passphrase is "mapped to a 32-bit value with XOR," the result of which is then used as the seed for a "linear congruential PRNG (which one of the several PRNGs Python has would fit this description, I don't know), and then from that result several bits of the result are taken. I have no idea how to go about implementing this, since the description is rather vague. What I need is help in writing the generator in Python, and also in understanding how exactly the key is generated. I'm not much of a programmer, so explanations are appreciated as well. (Yes, I know that WEP isn't secure.)

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  • Getting started with massive data

    - by Max
    I'm a math guy and occasionally do some statistics/machine learning analysis consulting projects on the side. The data I have access to are usually on the smaller side, at most a couple hundred of megabytes (and almost always far less), but I want to learn more about handling and analyzing data on the gigabyte/terabyte scale. What do I need to know and what are some good resources to learn from? Hadoop/MapReduce is one obvious start. Is there a particular programming language I should pick up? (I primarily work now in Python, Ruby, R, and occasionally Java, but it seems like C and Clojure are often used for large-scale data analysis?) I'm not really familiar with the whole NoSQL movement, except that it's associated with big data. What's a good place to learn about it, and is there a particular implementation (Cassandra, CouchDB, etc.) I should get familiar with? Where can I learn about applying machine learning algorithms to huge amounts of data? My math background is mostly on the theory side, definitely not on the numerical or approximation side, and I'm guessing most of the standard ML algorithms don't really scale. Any other suggestions on things to learn would be great!

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  • Where is my python script spending time? Is there "missing time" in my cprofile / pstats trace?

    - by fmark
    I am attempting to profile a long running python script. The script does some spatial analysis on raster GIS data set using the gdal module. The script currently uses three files, the main script which loops over the raster pixels called find_pixel_pairs.py, a simple cache in lrucache.py and some misc classes in utils.py. I have profiled the code on a moderate sized dataset. pstats returns: p.sort_stats('cumulative').print_stats(20) Thu May 6 19:16:50 2010 phes.profile 355483738 function calls in 11644.421 CPU seconds Ordered by: cumulative time List reduced from 86 to 20 due to restriction <20> ncalls tottime percall cumtime percall filename:lineno(function) 1 0.008 0.008 11644.421 11644.421 <string>:1(<module>) 1 11064.926 11064.926 11644.413 11644.413 find_pixel_pairs.py:49(phes) 340135349 544.143 0.000 572.481 0.000 utils.py:173(extent_iterator) 8831020 18.492 0.000 18.492 0.000 {range} 231922 3.414 0.000 8.128 0.000 utils.py:152(get_block_in_bands) 142739 1.303 0.000 4.173 0.000 utils.py:97(search_extent_rect) 745181 1.936 0.000 2.500 0.000 find_pixel_pairs.py:40(is_no_data) 285478 1.801 0.000 2.271 0.000 utils.py:98(intify) 231922 1.198 0.000 2.013 0.000 utils.py:116(block_to_pixel_extent) 695766 1.990 0.000 1.990 0.000 lrucache.py:42(get) 1213166 1.265 0.000 1.265 0.000 {min} 1031737 1.034 0.000 1.034 0.000 {isinstance} 142740 0.563 0.000 0.909 0.000 utils.py:122(find_block_extent) 463844 0.611 0.000 0.611 0.000 utils.py:112(block_to_pixel_coord) 745274 0.565 0.000 0.565 0.000 {method 'append' of 'list' objects} 285478 0.346 0.000 0.346 0.000 {max} 285480 0.346 0.000 0.346 0.000 utils.py:109(pixel_coord_to_block_coord) 324 0.002 0.000 0.188 0.001 utils.py:27(__init__) 324 0.016 0.000 0.186 0.001 gdal.py:848(ReadAsArray) 1 0.000 0.000 0.160 0.160 utils.py:50(__init__) The top two calls contain the main loop - the entire analyis. The remaining calls sum to less than 625 of the 11644 seconds. Where are the remaining 11,000 seconds spent? Is it all within the main loop of find_pixel_pairs.py? If so, can I find out which lines of code are taking most of the time?

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  • How can use the currently displayed node to filter a block-level view on that node's page?

    - by Deane
    I have parent/child relationship set up via Node Reference. A Child record can have a Parent record selected from a Node Reference field (this is optional -- I can have Parent-less Children as well). I've created a Views block to appear on the Parent pages, below the content. It's going to show a table of all the Child nodes for that Parent. Problem is, right now it shows every Child node. I need to filter it for just the Parent being displayed. What I need to be able to do is add a filter to this View to effectively say, "Only show the Child nodes that are assigned to the Parent being displayed on this page." So, somehow I need to be able to get the Nid of the currently displaying node (which will be a Parent, in all cases when this block is displayed), and use that in a filter in my View. How exactly can I do this? (Initially I used an attachment view for this (as this page instructs). I created a page view to display the Parent, then an attachment view to display all the Children, then attached that under the page view. This worked, but it was almost absurdly complicated to set up, and it was an undesirable for a number of other reasons -- primarily that my Parent now has two dedicated URLs, it's own node-level page, and the similar page created by this view.) Using Drupal 6.15.

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  • compareTo and nested Enums

    - by echox
    Hi, in "A Programmers Guide to Java SCJP Certification" I found an example which I can't follow. This the given enum: enum Scale3 { GOOD(Grade.C), BETTER(Grade.B), BEST(Grade.A); enum Grade {A, B, C} private Grade grade; Scale3(Grade grade) { this.grade = grade; } public Grade getGrade() { return grade; } } This is the given expression: Scale3.GOOD.getGrade().compareTo(Scale3.Grade.A) > 0; I don't understand why this expression will be true? The return value will be 2. compareTo() will return a value 0 if the given object is "less" than the object. Scale3.Grade.A is the "biggest" element of Grades, its ordinal number is 0. Scale3.GOOD is the "biggest" element of Scale3, its ordinal number is also 0. The constructor of Scale3 is called with Scale3.Grade.C, which ordinal number is 2. So the given expression is equal to the following code: Scale3.Grade.C.compareTo(Scale3.Grade.A) > 0; A is "bigger" than C, so shouldn't be the result < 0?

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  • Converting an int64 value to a Number object in JavaScript

    - by Matt
    I have a COM object which has a method that returns an unsigned int64 (VT_UI8) value. We have an HTML page which contains some JavaScript which can load the COM object and make the call to that method, to retrieve the value as such: var foo = MyCOMObject.GetInt64Value(); This value can easily be displayed to the user in a message dialog using: alert(foo); or displayed on the page by: document.getElementById('displayToUser').innerHTML = foo; However, we cannot use this value as a Number (e.g. if we try to multiply it by 2) without the page throwing "Number expected" errors. If we check "typeof(foo)" it returns "unknown". I've found a workaround for this by doing the following: document.getElementById('displayToUser').innerHTML = foo; var bar = parseInt(document.getElementById('displayToUser').innerHTML); alert(bar*2); What I need to know is how to make that process more efficient. Specifically, is there a way to cast foo to a String explicitly, rather than having to set some document element's innerHTML to foo and then retrieve it from that. I wouldn't mind calling something like: alert(parseInt((string)foo) * 2); Even better would be if there is a way to directly convert the int64 to a Number, without going through the String conversion, but I hold out less hope for that.

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  • Select * from 'many to many' SQL relationship

    - by Rampant Creative Group
    I'm still learning SQL and my brain is having a hard time with this one. Say I have 3 tables: teams players and teams_players as my link table All I want to do is run a query to get each team and the players on them. I tried this: SELECT * FROM teams INNER JOIN teams_players ON teams.id = teams_players.team_id INNER JOIN players ON teams_players.player_id = players.id But it returned a separate row for each player on each team. Is JOIN the right way to do it or should I be doing something else? ----------------------------------------- Edit Ok, so from what I'm hearing, this isn't necessarily a bad way to do it. I'll just have to group the data by team while I'm doing my loop. I have not yet tried the modified SQL statements provided, but I will today and get back to you. To answer the question about structure - I guess I wasn't thinking about the returned row structure which is part of what lead to my confusion. In this particular case, each team is limited to 4 players (or less) so I guess the structure that would be helpful to me is something like the following: teams.id, teams.name, players.id, players.name, players.id, players.name, players.id, players.name, players.id, players.name, 1 Team ABC 1 Jim 2 Bob 3 Ned 4 Roy 2 Team XYZ 2 Bob 3 Ned 5 Ralph 6 Tom

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  • Microsoft Detours - DetourUpdateThread?

    - by pault543
    Hi, I have a few quick questions about the Microsoft Detours Library. I have used it before (successfully), but I just had a thought about this function: LONG DetourUpdateThread(HANDLE hThread); I read elsewhere that this function will actually suspend the thread until the transaction completes. This seems odd since most sample code calls: DetourUpdateThread(GetCurrentThread()); Anyway, apparently this function "enlists" threads so that, when the transaction commits (and the detours are made), their instruction pointers are modified if they lie "within the rewritten code in either the target function or the trampoline function." My questions are: When the transaction commits, is the current thread's instruction pointer going to be within the DetourTransactionCommit function? If so, why should we bother enlisting it to be updated? Also, if the enlisted threads are suspended, how can the current thread continue executing (given that most sample code calls DetourUpdateThread(GetCurrentThread());)? Finally, could you suspend all threads for the current process, avoiding race conditions (considering that threads could be getting created and destroyed at any time)? Perhaps this is done when the transaction begins? This would allow us to enumerate threads more safely (as it seems less likely that new threads could be created), although what about CreateRemoteThread()? Thanks, Paul For reference, here is an extract from the simple sample: // DllMain function attaches and detaches the TimedSleep detour to the // Sleep target function. The Sleep target function is referred to // through the TrueSleep target pointer. BOOL WINAPI DllMain(HINSTANCE hinst, DWORD dwReason, LPVOID reserved) { if (dwReason == DLL_PROCESS_ATTACH) { DetourTransactionBegin(); DetourUpdateThread(GetCurrentThread()); DetourAttach(&(PVOID&)TrueSleep, TimedSleep); DetourTransactionCommit(); } else if (dwReason == DLL_PROCESS_DETACH) { DetourTransactionBegin(); DetourUpdateThread(GetCurrentThread()); DetourDetach(&(PVOID&)TrueSleep, TimedSleep); DetourTransactionCommit(); } return TRUE; }

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  • How close can I get C# to the performance of C++ for small intensive tasks?

    - by SLC
    I was thinking about the speed difference of C++ to C# being mostly about C# compiling to byte-code that is taken in by the JIT compiler (is that correct?) and all the checks C# does. I notice that it is possible to turn a lot of these functions off, both in the compile options, and possibly through using the unsafe keyword as unsafe code is not verifiable by the common language runtime. Therefore if you were to write a simple console application in both languages, that flipped an imaginary coin an infinite number of times and displayed the results to the screen every 10,000 or so iterations, how much speed difference would there be? I chose this because it's a very simple program. I'd like to test this but I don't know C++ or have the tools to compile it. This is my C# version though: static void Main(string[] args) { unsafe { Random rnd = new Random(); int heads = 0, tails = 0; while (true) { if (rnd.NextDouble() > 0.5) heads++; else tails++; if ((heads + tails) % 1000000 == 0) Console.WriteLine("Heads: {0} Tails: {1}", heads, tails); } } } Is the difference enough to warrant deliberately compiling sections of code "unsafe" or into DLLs that do not have some of the compile options like overflow checking enabled? Or does it go the other way, where it would be beneficial to compile sections in C++? I'm sure interop speed comes into play too then. To avoid subjectivity, I reiterate the specific parts of this question as: Does C# have a performance boost from using unsafe code? Do the compile options such as disabling overflow checking boost performance, and do they affect unsafe code? Would the program above be faster in C++ or negligably different? Is it worth compiling long intensive number-crunching tasks in a language such as C++ or using /unsafe for a bonus? Less subjectively, could I complete an intensive operation faster by doing this?

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  • Eclipse CDT setup for remote build

    - by Posco Grubb
    Is there a better way to setup Eclipse CDT for local editing and remote building? I am working on a C++ project that uses GNU make in Linux. The code is under CVS on a Linux server. When I'm in the lab, I use Eclipse CDT on a Linux-x64 PC. The project is built on a Linux-x86 PC. All the computers in the lab (including the CVS server) have NFS mounts. When I'm at home, I use Eclipse CDT on a Windows 7 PC. The Windows PC connects to the Linux CVS server via SSH tunnel. To edit source, I rsync the C++ project under the Linux Eclipse workspace back to my Windows Eclipse workspace. (I can also do a remote CVS checkout on the Windows PC.) To build from home, I use a custom build command that SSH's to the Linux-x86 PC, rsync's the C++ project from my Windows Eclipse workspace to my Linux Eclipse workspace, and then runs make on the Liunx-x86 PC, specifying the correct path for the Makefile. In order to go back and forth between lab and home without committing my changes to CVS every time, I use rsync. When I transition from lab to home, I rsync sources to my Windows Eclipse workspace. When I build from home, the sources get rsync'd back to the Linux Eclipse workspace. Is there a better, less wonky way to do this? (I'm NOT interested in remote debugging.)

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  • TranslateTransform for drag and drop in Silverlight

    - by fuzzyman
    We're trying to implement drag and drop in Silverlight (3). We want users to be able to drag elements from a treeview onto another part of a UI. The parent element is a Grid, and we've been trying to use a TranslateTransform along with the MouseLeftButtonDown, MouseMove (etc) events, as recommended by various online examples. For example: http://www.85turns.com/2008/08/13/drag-and-drop-silverlight-example/ We're doing this in IronPython, but that should be more or less irrelevant. The drag start is correctly initiated, but the item we are dragging appears in the 'wrong' location (offset a few hundred pixels to the right and down from the cursor) and I can't for the life of me work out why. Basic xaml: <Grid x:Name="layout_root"> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition Height="120"/> </Grid.RowDefinitions> <Border x:Name="drag" Background="LightGray" Width="40" Height="15" Visibility="Collapsed" Canvas.ZIndex="10"> <Border.RenderTransform> <TranslateTransform x:Name="transform" X="0" Y="0" /> </Border.RenderTransform> <TextBlock x:Name="dragText" TextAlignment="Center" Foreground="Gray" Text="foo" /> </Border> ... </Grid> The startDrag method is triggered by the MouseLeftButtonDown event (on a TextBlock in a TreeViewItem.Header). onDrag is triggered by MouseMove. In the following code self.root is Application.Current.RootVisual (top level UI element from app.xaml): def startDrag(self, sender, event): self.root.drag.Visibility = Visibility.Visible self.root.dragText.Text = sender.Text position = event.GetPosition(self.root.drag.Parent) self.root.drag.transform.X = position.X self.root.drag.transform.Y = position.Y self.root.CaptureMouse() self._captured = True def onDrag(self, sender, event): if self._captured: position = event.GetPosition(self.root.drag.Parent) self.root.drag.transform.X = position.X self.root.drag.transform.Y = position.Y The dragged item follows the mouse move, but is offset considerably. Any idea what I am doing wrong and how to correct it?

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  • RFC: Whitespace's Assembly Mnemonics

    - by Noctis Skytower
    Request For Comment regarding Whitespace's Assembly Mnemonics What follows in a first generation attempt at creating mnemonics for a whitespace assembly language. STACK ===== push number copy copy number swap away away number MATH ==== add sub mul div mod HEAP ==== set get FLOW ==== part label call label goto label zero label less label back exit I/O === ochr oint ichr iint In the interest of making improvements to this small and simple instruction set, this is a second attempt. 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 add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo save Store load Retrieve 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 exit End the program 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 What is the general consensus on the following revised list for Whitespace's assembly instructions? They definitely come from thinking outside of the box and trying to come up with a better mnemonic set than last time. When the previous python interpreter was written, it was completed over two contiguous, rushed evenings. This rewrite deserves significantly more time now that it is the summer. Of course, the next version of Whitespace (0.4) may have its instructions revised even more, but this is just a redesign of what originally was done in a few hours. Hopefully, the instructions make more sense to those new to programming jargon.

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  • need primitive public key signature with out of band key distribution

    - by Mike D
    I pretty much a complete neophyte at this signature business so I don't know if what I'm asking is nonsense or not. Anyway, here goes... I want to send an out of band message (don't worry about how it gets there) to a program I've written on a distant machine. I want the program to have some confidence the message is legit by attaching a digital signature to the message. The message will be small less than 200 characters. It seems a public key based signature is what I want to use. I could embed the public key in the program. I understand that the program would be vulnerable to attack by anyone who modifies it BUT I'm not too worried about that. The consequences are not dire. I've looked through the MSDN and around the web but the prospect of diving in is daunting. I'm writing in straight c++, no NET framework or other fancy stuff. I've had no experience including NET framework stuff and little luck during previous attempts. Can anyone point me at some very basic resources to get me started? I need to know 1)how to generate the public and private keys 2)how to sign the message 3)how to verify the signature Any help much appreciated. TIA, Mike

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  • What are practical guidelines for evaluating a language's "Turing Completeness"?

    - by AShelly
    I've read "what-is-turing-complete" and the wikipedia page, but I'm less interested in a formal proof than in the practical implications of being Turing Complete. What I'm actually trying to decide is if the toy language I've just designed could be used as a general-purpose language. I know I can prove it is if I can write a Turing machine with it. But I don't want to go through that exercise until I'm fairly certain of success. Is there a minimum set of features without which Turing Completeness is impossible? Is there a set of features which virtually guarantees completeness? (My guess is that conditional branching and a readable/writeable memory store will get me most of the way there) EDIT: I think I've gone off on a tangent by saying "Turing Complete". I'm trying to guess with reasonable confidence that a newly invented language with a certain feature set (or alternately, a VM with a certain instruction set) would be able to compute anything worth computing. I know proving you can building a Turing machine with it is one way, but not the only way. What I was hoping for was a set of guidelines like: "if it can do X,Y,and Z, it can probably do anything".

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  • notify listener inside or outside inner synchronization

    - by Jary Zeels
    Hello all, I am struggling with a decision. I am writing a thread-safe library/API. Listeners can be registered, so the client is notified when something interesting happens. Which of the two implementations is most common? class MyModule { protected Listener listener; protected void somethingHappens() { synchronized(this) { ... do useful stuff ... listener.notify(); } } } or class MyModule { protected Listener listener; protected void somethingHappens() { Listener l = null; synchronized(this) { ... do useful stuff ... l = listener; } l.notify(); } } In the first implementation, the listener is notified inside the synchronization. In the second implementation, this is done outside the synchronization. I feel that the second one is advised, as it makes less room for potential deadlocks. But I am having trouble to convince myself. A downside of the second imlementation is that the client might receive 'incorrect' notifications, which happens if it accessed the module prior to the l.notify() statement. thanks a lot

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  • what libraries or platforms should I use to build web apps that provide real-time, asynchronous data

    - by Daniel Sterling
    This is a less a question with a simple, practical answer and more a question to foster discussion on the real-time data exchange topic. I'll begin with an example: Google Wave is, at its core, a real-time asynchronous data synchronization engine. Wave supports (or plans to support) concurrent (real-time) document collaboration, disconnected (offline) document editing, conflict resolution, document history and playback with attribution, and server federation. A core part of Wave is the Operational Transformation engine: http://www.waveprotocol.org/whitepapers/operational-transform The OT engine manages document state. Changes between clients are merged and each client has a sane and consistent view of the document at all times; the final document is eventually consistent between all connected clients. My question is: is this system abstract or general enough to be used as a library or generic framework upon which to build web apps that synchronize real-time, asynchronous state in each client? Is the Wave protocol directly used by any current web applications (besides Google's client)? Would it make sense to directly use it for generic state synchronization in a web app? What other existing libraries or frameworks would you consider using when building such a web app? How much code in such an app might be domain-specific logic vs generic state synchronization logic? Or, put another way, how leaky might the state synchronization abstractions be? Comments and discussion welcomed!

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  • Haskell math performance

    - by Travis Brown
    I'm in the middle of porting David Blei's original C implementation of Latent Dirichlet Allocation to Haskell, and I'm trying to decide whether to leave some of the low-level stuff in C. The following function is one example—it's an approximation of the second derivative of lgamma: double trigamma(double x) { double p; int i; x=x+6; p=1/(x*x); p=(((((0.075757575757576*p-0.033333333333333)*p+0.0238095238095238) *p-0.033333333333333)*p+0.166666666666667)*p+1)/x+0.5*p; for (i=0; i<6 ;i++) { x=x-1; p=1/(x*x)+p; } return(p); } I've translated this into more or less idiomatic Haskell as follows: trigamma :: Double -> Double trigamma x = snd $ last $ take 7 $ iterate next (x' - 1, p') where x' = x + 6 p = 1 / x' ^ 2 p' = p / 2 + c / x' c = foldr1 (\a b -> (a + b * p)) [1, 1/6, -1/30, 1/42, -1/30, 5/66] next (x, p) = (x - 1, 1 / x ^ 2 + p) The problem is that when I run both through Criterion, my Haskell version is six or seven times slower (I'm compiling with -O2 on GHC 6.12.1). Some similar functions are even worse. I know practically nothing about Haskell performance, and I'm not terribly interested in digging through Core or anything like that, since I can always just call the handful of math-intensive C functions through FFI. But I'm curious about whether there's low-hanging fruit that I'm missing—some kind of extension or library or annotation that I could use to speed up this numeric stuff without making it too ugly.

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  • Defining < for STL sort algorithm - operator overload, functor or standalone function?

    - by Andy
    I have a stl::list containing Widget class objects. They need to be sorted according to two members in the Widget class. For the sorting to work, I need to define a less-than comparator comparing two Widget objects. There seems to be a myriad of ways to do it. From what I can gather, one can either: a. Define a comparison operator overload in the class: bool Widget::operator< (const Widget &rhs) const b. Define a standalone function taking two Widgets: bool operator<(const Widget& lhs, const Widget& rhs); And then make the Widget class a friend of it: class Widget { // Various class definitions ... friend bool operator<(const Widget& lhs, const Widget& rhs); }; c. Define a functor and then include it as a parameter when calling the sort function: class Widget_Less : public binary_function<Widget, Widget, bool> { bool operator()(const Widget &lhs, const Widget& rhs) const; }; Does anybody know which method is better? In particular I am interested to know if I should do 1 or 2. I searched the book Effective STL by Scott Meyer but unfortunately it does not have anything to say about this. Thank you for your reply.

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  • VB.NET vs. C#.NET?

    - by Onion-Knight
    Hello everyone, The company I work for has all of its legacy ("legacy" being used rather liberally in this context) code in VB.NET. They have about 6000+ lines of VB.NET code, so all of the developers are comfortable with it. We have started to develop a new product, and are finding that some modules are easier to complete in C# than in VB.NET, such as Interprocess Communication via WCF. The things our product will eventually need to do are as follows: Communicate via IPC between Windows Services, Silverlight, and WinForms Handle parallization, and all the complexity that comes along with it Windows Service and WinForms development ASP.NET, AJAX, and Silverlight development Database (SQL) access Lots of event handling (Sync and Async events) My question is: Given the type of work we will be doing to complete our product, are there features of one language that will make life easier that the other does not have? And if so, it is worth asking the developers to switch to a language they are less comfortable with? I was hoping to keep this as objective as possible, by listing exactly what type of work we will be doing with the product. Please don't turn this into a VB/C# holy war. Thanks, Onion-Knight

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  • DataTable won't DataBind with a DataTable.NewRow()

    - by David
    Is DataRow.NewRow() insufficient as the only row in a DataTable? I would expect this to work, but it doesn't. It's near the end of my Page_Load inside my If(!Postback) block. gridCPCP is GridView DataTable dt = new DataTable(); dt.Columns.Add("ID", int.MinValue.GetType()); dt.Columns.Add("Code", string.Empty.GetType()); dt.Columns.Add("Date", DateTime.MinValue.GetType()); dt.Columns.Add("Date2", DateTime.MinValue.GetType()); dt.Columns.Add("Filename", string.Empty.GetType()); //code to add rows if (dt.Rows.Count > 0) { gridCPCP.DataSource = dt; gridCPCP.DataBind(); } else { dt.Rows.Add(dt.NewRow()); gridCPCP.DataSource = dt; gridCPCP.DataBind(); //EXCEPTION int TotalColumns = gridCPCP.Rows[0].Cells.Count; gridCPCP.Rows[0].Cells.Clear(); gridCPCP.Rows[0].Cells.Add(new TableCell()); gridCPCP.Rows[0].Cells[0].ColumnSpan = TotalColumns; gridCPCP.Rows[0].Cells[0].Text = "No Record Found"; } The exception throws on gridCPCP.DataBind() and only when execution reaches the else block. If there were rows added above via dt.Rows.Add(new object[] { ... } binding works. System.ArgumentOutOfRangeException: Length cannot be less than zero. Parameter name: length

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