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• iPhone OpenGL ES Texture2D Masking

  - by Robert Neagu

  What's the best choice when trying to mask a texture like ColorSplash or other apps like iSteam, etc? I started learning OPENGL ES like... 4 days ago (I'm a total rookie) and tried the following approach: 1) I created a colored texture2D, a grayscale version of the first texture and a third texture2D called mask 2) I also created a texture2D for the brush... which is grayscale and it's opaque (brush = black = 0,0,0,1 and surroundings = white = 1,1,1,1). My intention was to create an antialiased brush with smooth edges but i'm fine with a normal one right now 3) I searched for masking techniques on the internet and found this tutorial ZeusCMD - Design and Development Tutorials : OpenGL ES Programming Tutorials - Masking about masking. The tutorial tells me to use blending to achieve masking... first draw colored, then mask with glBlendFunc(GL_DST_COLOR, GL_ZERO) and then grayscale with glBlendFunc(GL_ONE, GL_ONE) ... and this gives me something close to what i want... but not exactly what i want. The result is masked but it's somehow overbright-ed 4) For drawing to the mask texture i used an extra frame buffer object (FBO) I'm not really happy with the resulting image (overbright-ed picture) nor with the speed achieved with this method. I think the normal way was to draw directly to the grayscale (overlay) texture2D affecting only it's alpha channel in the places where the brush hits. Is there a fast way to achieve this? I have searched a lot and never got an answer that's clear and understandable. Then, in the main draw loop I could only draw the colored texture and then blend the grayscale ontop with glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA). I just want to learn to use OPENGL ES and it's driving me nuts because i can't get it to work properly. An advice, a link to a tutorial would be much appreciated.

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• Trie Backtracking in Recursion

  - by Darksky

  I am building a tree for a spell checker with suggestions. Each node contains a key (a letter) and a value (array of letters down that path). So assume the following sub-trie in my big trie: W / \ a e | | k k | | is word--> e e | ... This is just a subpath of a sub-trie. W is a node and a and e are two nodes in its value array etc... At each node, I check if the next letter in the word is a value of the node. I am trying to support mistyped vowels for now. So 'weke' will yield 'wake' as a suggestion. Here's my searchWord function in my trie: def searchWord(self, word, path=""): if len(word) > 0: key = word[0] word = word[1:] if self.values.has_key(key): path = path + key nextNode = self.values[key] return nextNode.searchWord(word, path) else: # check here if key is a vowel. If it is, check for other vowel substitutes else: if self.isWord: return path # this is the word found else: return None Given 'weke', at the end when word is of length zero and path is 'weke', my code will hit the second big else block. weke is not marked as a word and so it will return with None. This will return out of searchWord with None. To avoid this, at each stack unwind or recursion backtrack, I need to check if a letter is a vowel and if it is, do the checking again. I changed the if self.values.has_key(key) loop to the following: if self.values.has_key(key): path = path + key nextNode = self.values[key] ret = nextNode.searchWord(word, path) if ret == None: # check if key == vowel and replace path # return nextNode.searchWord(... return ret What am I doing wrong here? What can I do when backtracking to achieve what I'm trying to do?

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• Easiest way to specify the selected option to a dropdown list in ASP.NET MVC

  - by sdr

  I have a list of options (IEnumerable< SelectListItem ) in my model that I want to use in multiple dropdowns in my view. But each of these dropdowns could have a different selected option. Is there an easy way to simply specfiy which should be selected if using the Html.DropDownList helper? At this point, the only way I can see is to generate the html myself and loop through the list of options like so: <% for(int i=0; i<10; i++) { %> <select name="myDropDown<%= i %>"> <% foreach(var option in Model.Options) { %> <option value="<%= Html.Encode(option.optValue) %>" <%if(ShouldBeSelected(i)) {%> selected="selected"<% } %>><%= Html.Encode(option.optText) %></option> <% } %> </select> <% } %>

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• How to avoid resetting the java Scanner position

  - by Derek

  I have some code that looks more or less like this: while(scanner.hasNext()) { if(scanner.findInLine("Test") !=null) { //do some things }else{ scanner.nextLine(); } } I am using this to parse an ~10MB text file. The problem is, if I put a breakpoint on the while() and the scanner.nextLine(), I can see that sometimes the scanners position (in the debug window) goes back to zero. I think this is causing me some kind of loop blow up, because the regext in findInLine() starts at zero, looks through some amount of text, advancing the position, and then it randomly gets set back to zero, so it has to re-parse all that text again. Any ideas what can be causing that? Am I even doing this the right way? Thanks Some additional info: The Scanner is instantiated from an InputStream. After diubg sine debugging, it appears that there is a HearCharBuffer that Scanner uses and it only allows 1024 characters at a time, and then resets. Is there a way to avoid this, or do things differently? That seems like a small amount of characters to be able to scan. Derek

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• When and why can sprintf fail?

  - by Srekel

  I'm using swprintf to build a string into a buffer (using a loop among other things). const int MaxStringLengthPerCharacter = 10 + 1; wchar_t* pTmp = pBuffer; for ( size_t i = 0; i < nNumPlayers ; ++i) { const int nPlayerId = GetPlayer(i); const int nWritten = swprintf(pTmp, MaxStringLengthPerCharacter, TEXT("%d,"), nPlayerId); assert(nWritten >= 0 ); pTmp += nWritten; } *pTaskPlayers = '\0'; If during testing the assert never hits, can I be sure that it will never hit in live code? That is, do I need to check if nWritten < 0 and handle that, or can I safely assume that there won't be a problem? Under which circumstances can it return -1? The documentation more or less just states "If the function fails". In one place I've read that it will fail if it can't match the arguments (i.e. the formatting string to the varargs) but that doesn't worry me. I'm also not worried about buffer overrun in this case - I know the buffer is big enough.

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• Qt cross thread call

  - by QLatvia

  I have a Qt/C++ application, with the usual GUI thread, and a network thread. The network thread is using an external library, which has its own select() based event loop... so the network thread isn't using Qt's event system. At the moment, the network thread just emit()s signals when various events occur, such as a successful connection. I think this works okay, as the signals/slots mechanism posts the signals correctly for the GUI thread. Now, I need for the network thread to be able to call the GUI thread to ask questions. For example, the network thread may require the GUI thread to request put up a dialog, to request a password. Does anyone know a suitable mechanism for doing this? My current best idea is to have the network thread wait using a QWaitCondition, after emitting an object (emit passwordRequestedEvent(passwordRequest);. The passwordRequest object would have a handle on the particular QWaitCondition, and so can signal it when a decision has been made.. Is this sort of thing sensible? or is there another option?

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• Strange problem with simple multithreading program in Java

  - by Elizabeth

  Hello, I am just starting play with multithreading programming. I would like to my program show alternately character '-' and '+' but it doesn't. My task is to use synchronized keyword. As far I have: class FunnyStringGenerator{ private char c; public FunnyStringGenerator(){ c = '-'; } public synchronized char next(){ if(c == '-'){ c = '+'; } else{ c = '-'; } return c; } } class ThreadToGenerateStr implements Runnable{ FunnyStringGenerator gen; public ThreadToGenerateStr(FunnyStringGenerator fsg){ gen = fsg; } @Override public void run() { for(int i = 0; i < 10; i++){ System.out.print(gen.next()); } } } public class Main{ public static void main(String[] args) throws IOException { FunnyStringGenerator FSG = new FunnyStringGenerator(); ExecutorService exec = Executors.newCachedThreadPool(); for(int i = 0; i < 20; i++){ exec.execute(new ThreadToGenerateStr(FSG)); } } } EDIT: I also testing Thread.sleep in run method instead for loop.

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• adding an uncertain number of fields using javascript

  - by user306472

  I'm new to javascript and a novice programmer, so this might be a really easy question to answer. I would like to loop over the values of x number of fields and add them up to display the sum in a final field. I can perform this function if I explicitly call each field, but I want to abstract this so I can deal with a flexible number of fields. Here's example code I've come up with (that's not working for me). Where am I going wrong? <html> <head> <script type="text/javascript"> function startAdd(){ interval = setInterval("addfields()",1); } function addfields(){ a = document.addition.total.value; b = getElementByTagName("sum").value; for (i=0; i<=b.length; i++){ a+=i; } return a; } function stopAdd(){ clearInterval(interval); } </script> </head> <body> <form name="addition"> <input type="text" name="sum" onFocus="startAdd();" onBlur="stopAdd;"> + <input type="text" name="sum" onFocus="startAdd();" onBlur="stopAdd;"> = <input type="text" name ="total"> </form> </body> </html>

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• Why are compilers so stupid?

  - by martinus

  I always wonder why compilers can't figure out simple things that are obvious to the human eye. They do lots of simple optimizations, but never something even a little bit complex. For example, this code takes about 6 seconds on my computer to print the value zero (using java 1.6): int x = 0; for (int i = 0; i < 100 * 1000 * 1000 * 1000; ++i) { x += x + x + x + x + x; } System.out.println(x); It is totally obvious that x is never changed so no matter how often you add 0 to itself it stays zero. So the compiler could in theory replace this with System.out.println(0). Or even better, this takes 23 seconds: public int slow() { String s = "x"; for (int i = 0; i < 100000; ++i) { s += "x"; } return 10; } First the compiler could notice that I am actually creating a string s of 100000 "x" so it could automatically use s StringBuilder instead, or even better directly replace it with the resulting string as it is always the same. Second, It does not recognize that I do not actually use the string at all, so the whole loop could be discarded! Why, after so much manpower is going into fast compilers, are they still so relatively dumb? EDIT: Of course these are stupid examples that should never be used anywhere. But whenever I have to rewrite a beautiful and very readable code into something unreadable so that the compiler is happy and produces fast code, I wonder why compilers or some other automated tool can't do this work for me.

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• most efficient method of turning multiple 1D arrays into columns of a 2D array

  - by Ty W

  As I was writing a for loop earlier today, I thought that there must be a neater way of doing this... so I figured I'd ask. I looked briefly for a duplicate question but didn't see anything obvious. The Problem: Given N arrays of length M, turn them into a M-row by N-column 2D array Example: $id = [1,5,2,8,6] $name = [a,b,c,d,e] $result = [[1,a], [5,b], [2,c], [8,d], [6,e]] My Solution: Pretty straight forward and probably not optimal, but it does work: <?php // $row is returned from a DB query // $row['<var>'] is a comma separated string of values $categories = array(); $ids = explode(",", $row['ids']); $names = explode(",", $row['names']); $titles = explode(",", $row['titles']); for($i = 0; $i < count($ids); $i++) { $categories[] = array("id" => $ids[$i], "name" => $names[$i], "title" => $titles[$i]); } ?> note: I didn't put the name = value bit in the spec, but it'd be awesome if there was some way to keep that as well.

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• Nested loops through recursion with usable iterators

  - by narandzasto

  Help! I need to generate a query with loops,but there must be undefinitly numbers of loop or much as many a client wants. I know that it can be done with recursion,but don't know exectly how.One more thing. Notice,please,that I need to use those k,i,j iterators later in "if" condition and I don't know how to catch them. Thanks class Class1 { public void ListQuery() { for (int k = 0; k < listbox1.Count; k++) { for (int i = 0; i < listbox2.Count; i++) { for (int j = 0; j < listbox3.Count; j++) { if (k == listbox1.count-1 && i == listbox2.count-1 && j == listbox3.count-1) { if (!checkbox1) Query += resultset.element1 + "=" + listbox1[k]; if (!checkbox2) Query += resultset.element2 + "=" + listbox1[i]; if (!checkbox3) Query += resultset.element3 + "=" + listbox1[j]; } } } } } }

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• PIC C - Sending 200 values over USB, but it only sends 25 of them...

  - by Adam

  I have a PIC18F4455 microcontroller which I am trying to use to send 200 values over USB. Basically I am using a for loop and a printf statement to print the values to the usb output stream. However, when the code executes I see in my serial port monitor that it is only sending the first 25 values, then stopping. My PIC C code is below. It will send out the 25th value (and the comma), but not send anything after and not send a newline character. I'm trying to get it to send all the values, then a newline character at the end. I am sending them all as characters because I can convert them on the PC end of it. //print #3 for (i = 0; i <= 199; i++){if (data[i]=='\0' || data[i]=='\n'){data[i]++;}} for (i = 0; i < 199; i++){printf(usb_cdc_putc, "%c,", data[i]);} printf(usb_cdc_putc, "%c\n", data[199]);

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• jquery.append() - only the last element of my list is appended, previous ones are erased

  - by jaes

  Hi, I have a page like this : <div id="daysTable"> <div id="day0" class="day"></div> <div id="day1" class="day"></div> <div id="day2" class="day"></div> <div id="day3" class="day"></div> <div id="day4" class="day"></div> <div id="day5" class="day"></div> <div id="day6" class="day"></div> </div> and some javascript to fill my calendar like this function getWeek(){ $.getJSON("/getWeek",function(events){ var eventHeight = $("#hoursTable > div").height(); var eventWidth = $("#daysTable > div").width(); var startWeek = events[0]// timestamp of the start of the week for(var i = 1; i < events.length; i ++){ $(".day").empty(); var startHour = (events[i].startDate - startWeek)/3600 var duration = (events[i].stopDate - startWeek)/3600 - startHour var dayStart = Math.floor(startHour/24); var startHour = startHour - dayStart * 24 divEvent = $('<div id="event'+events[i].idEvent+'"/>') .width(eventWidth-2) .height(duration*eventHeight) .css("border","1px solid black") .css("margin-top",startHour*eventHeight) .html(events[i].name); divEvent.appendTo("#day"+dayStart); console.log(divEvent); } }); } my problem being : events contain 3 element I'd like to display but only the last is displayed. If I stop my "for" at the first iteration I can see the first div appended, but it seems that if my loop goes for three iteration the two previous are deleted. The console.log() display some "not-anymore" existing element. Any idea ?

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• How to decrypt a string encrypted with HMACSHA1?

  - by Bob

  I'm an encryption novice trying to pass some values back and forth between systems. I can encrypt the value, but can't seem to figure out how to decrypt on the other end. I've created a simple Windows Forms application using VB.NET. Trying to input a value and a key, encrypt and then decrypt to get the original value. Here's my code so far. Any help greatly appreciated. Thanks. Imports System Imports System.IO Imports System.Security.Cryptography Imports System.Text Public Class Form1 Private Sub btnEncode_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEncode.Click Dim hmacsha1 As New HMACSHA1(Encoding.ASCII.GetBytes(txtKey.Text)) Dim hashValue As Byte() = hmacsha1.ComputeHash(Encoding.ASCII.GetBytes(txtValue.Text)) txtResult.Text = BytesToHexString(hashValue) hmacsha1.Clear() End Sub Private Sub btnDecode_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDecode.Click '??? End Sub Private Function BytesToHexString(ByVal bytes As Byte()) As String Dim output As String = String.Empty Dim i As Integer = 0 Do While i < bytes.Length output += bytes(i).ToString("X2") i += 1 Loop Return output End Function End Class

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• Weird exception: Cannot cast String to Boolean when using getBoolean

  - by La bla bla

  I'm getting a very weird error. I have 2 activities. On both I'm getting the SharedPreferences using MODE_PRIVATE (if it matters) by sp = getPreferences(MODE_PRIVATE); on each activity's onCreate() I'm calling sp.getBoolean(IntroActivity.SHOW_INTRO, true) On the IntroActivity this works fine. But when I'm trying in the main activity, I'm getting this 10-12 04:55:23.208: E/AndroidRuntime(11668): FATAL EXCEPTION: main 10-12 04:55:23.208: E/AndroidRuntime(11668): java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean 10-12 04:55:23.208: E/AndroidRuntime(11668): at android.app.SharedPreferencesImpl.getBoolean(SharedPreferencesImpl.java:242) 10-12 04:55:23.208: E/AndroidRuntime(11668): at com.lablabla.parkme.ParkMeActivity$2.onClick(ParkMeActivity.java:194) 10-12 04:55:23.208: E/AndroidRuntime(11668): at android.view.View.performClick(View.java:4084) 10-12 04:55:23.208: E/AndroidRuntime(11668): at android.view.View$PerformClick.run(View.java:16966) 10-12 04:55:23.208: E/AndroidRuntime(11668): at android.os.Handler.handleCallback(Handler.java:615) 10-12 04:55:23.208: E/AndroidRuntime(11668): at android.os.Handler.dispatchMessage(Handler.java:92) 10-12 04:55:23.208: E/AndroidRuntime(11668): at android.os.Looper.loop(Looper.java:137) 10-12 04:55:23.208: E/AndroidRuntime(11668): at android.app.ActivityThread.main(ActivityThread.java:4745) 10-12 04:55:23.208: E/AndroidRuntime(11668): at java.lang.reflect.Method.invokeNative(Native Method) 10-12 04:55:23.208: E/AndroidRuntime(11668): at java.lang.reflect.Method.invoke(Method.java:511) 10-12 04:55:23.208: E/AndroidRuntime(11668): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 10-12 04:55:23.208: E/AndroidRuntime(11668): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 10-12 04:55:23.208: E/AndroidRuntime(11668): at dalvik.system.NativeStart.main(Native Method) I made sure that I'm not putting a String somewhere in the middle with that same key Any ideas? Thanks! EDIT: some code: //onCreate() sp = getPreferences(MODE_PRIVATE); // other method boolean showIntro = sp.getBoolean(IntroActivity.SHOW_INTRO, true); // Exception is here showIntroCheckBox.setChecked(showIntro); If it matters, the code which throws the exception is inside a button's onClick

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• need to display info for user within active-directory

  - by Brad

  The following code will search for the user within the domain controller, but I want to display the info of each thing noted within the justthese variable: "displayname","mail","samaccountname","sn","givenname","department","telephonenumber" $dn = "dc=xxx,dc=xxx"; $justthese = array("displayname","mail","samaccountname","sn","givenname","department","telephonenumber"); $sr=ldap_search($ldapconn, $dn,'SAMAccountName=username', $justthese); $info = ldap_get_entries($ldapconn, $sr); echo "<h3>".$info["count"]." entries returned</h3>"; foreach($justthese as $key=>$value){ print '<p><strong>'.$value.'</strong></p>'; } It displays each item within the $justthese array, I want to display the info for that user for each thing noted in $justthese array. Right now it outputs it like this: displayname mail samaccountname sn givenname department telephonenumber I want it to have the actual data to the right of it, which I know I am doing something wrong with the foreach loop, any help is appreciated. So it'd look like this displayname Chuck mail [email protected] samaccountname chucknorris sn chuckisthebest givenname Chuck Norris department Security telephonenumber 555-555-5555

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• A potentially dangerous Request.Form value was detected: Dealing with these errors proactively, or a

  - by Albert

  I'm noticing this error more and more in my error logs. I've read through the questions here talking about this error, but they don't address what I would like to do (see below). I'm considering three options, in the order of preference: 1) When submitting a form (I use formviews almost exclusively, if that helps), if potentially dangerous characters are detected, automatically strip them out and submit. 2) When submitting a form, if potentially dangerous characters are detected, alert the user and let them fix it before trying again. 3) After the exception is generated, deal with it and alert the user. I'm hoping one of the first two options might be able to do somewhat globally...I know for the 3rd I'd have to alter a TON of Try-Catch blocks I already have in place. Doable, but labor intensive. I'd rather be proactive about it if at all possible and avoid the exception all together. Perhaps one approach to #1 would be to write a block of code that could loop through all text entry fields in a formview, during the insert/update event, and strip the characters out. I'm ok with that, but I'd rather not have to heavily alter all my Insert/Update events to accomplish this. Or maybe I just create a different class to do the text checking/deleting, and only insert 1 line of code in each Insert/Update event. If anyone can come up with some example code of any of these approaches that would be a help. Thanks for any ideas or information. I'm definitely open to other solutions too; these are only the 3 that came to mind. I can say that I don't want to turn request validation off though.

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• Java function changing input

  - by Doodle

  I would like to go from one number to another. For example if I started at 6 and my goal was 10 I want a function that on every pass would bring me from 6 towards 10 or if I had the number 14 and my goal was 9 it would count down from 14 towards 9.So far I have (this is written in Processing a Java Api but there is essentially no difference from regualr Java, draw is just a continuous loop) int x=100; void draw(){ x=towards(x,10); println(x); } int towards(int current ,int target){ if(current!=target){ if (current <target){ current=current+1; } else { current=current-1; } } return current; } this gives me the results I would like but I would like to have everything in side of the towards() function. When I replace X with a variable it of course resets it self to the static variable. To sum it up how can I pass a variable to a function and have that variable thats been passed change on every subsequent pass. I have looked into recursion as a solution but that of just brings me to a final solution. I can pass the count to an array but wouldn't like to do that either.

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• PIC C - Sending 200 values over USB, but it only sends 25 or so of them...

  - by Adam

  I have a PIC18F4455 microcontroller which I am trying to use to send 200 values over USB. Basically I am using a for loop and a printf statement to print the values to the usb output stream. However, when the code executes I see in my serial port monitor that it is only sending the first 25 or so values, then stopping. My PIC C code is below. It will send out the 25th or so value (and the comma), but not send anything after and not send a newline character. I'm trying to get it to send all the values, then a newline character at the end. I am sending them all as characters because I can convert them on the PC end of it. //print #3 for (i = 0; i <= 199; i++){if (data[i]=='\0' || data[i]=='\n'){data[i]++;}} for (i = 0; i < 199; i++){printf(usb_cdc_putc, "%c,", data[i]);} printf(usb_cdc_putc, "%c\n", data[199]);

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• Using django and django-voting app, how can I order a queryset according to the votes of each item?

  - by snz3

  (I'm new to python and django so please bear with me for a second. I apologise if this has been answered elsewhere and couldn't find it) Let's say I have a Link model and through the django-voting application users can vote on link instances. How can I order those link instances according to their score, eg. display those with the higher score first. I assume I could use the get_top manager of django-voting, but that would only give me the top scoring link instances and wouldn't take into consideration other parameters I would like to add (for example, those links that belong to a specific user or paging or whatever). My guess would be to write a custom manager for my Link model where by I can filter a queryset according to each item's score. If I understand correctly that will require me to loop through each item, check its score, and then place it a list (or dictionary) which will then be sorted according to the score of each item. That wouldn't return a queryset but a dictionary with each item. Am I missing something here?

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• prolog recursion

  - by AhmadAssaf

  am making a function that will send me a list of all possible elemnts .. in each iteration its giving me the last answer .. but after the recursion am only getting the last answer back .. how can i make it give back every single answer .. thank you the problem is that am trying to find all possible distributions for a list into other lists .. the code test :- bp(3,12,[7, 3, 5, 4, 6, 4, 5, 2], Answer), format("Answer = ~w\n",[Answer]). bp(NB,C,OL,A):- addIn(C,OL,[[],[],[]],A); bp(NB,C,_,A). addIn(_,[],Result,Result). addIn(C,[Element|Rest],[F|R],Result):- member( Members , [F|R]), sumlist( Members, Sum), sumlist([Element],ElementLength), Cap is Sum + ElementLength, (Cap =< C, append([Element], Members,New), insert( Members, New, [F|R], PartialResult), addIn(C,Rest,PartialResult,Result)). by calling test .. am getting back all the list of possible answers .. now if i tried to do something that will fail like bp(3,11,[8,2,4,6,1,8,4],Answer). it will just enter a while loop .. more over if i changed the bp(NB,C,OL,A):- addIn(C,OL,[[],[],[]],A); bp(NB,C,_,A). to and instead of Or .. i get error : ERROR: is/2: Arguments are not sufficiently instantiated appreciate the help .. Thanks alot @hardmath

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• Connections hanging on read()

  - by viraptor

  Hi, Short version: I've got a strange issue with a server accepting TCP connections. Even though there are normally some processes waiting, at some volume of connections it hangs. Long version: The server is written in Perl and binds a $srv socket with the reuse flag and listen == 5. Afterwards, it forks into 10 processes with a loop of $clt=$srv->accept(); do_processing($clt); $clt->shutdown(2); The client written in C is also very simple - it sends some lines, then receives all lines available and does a shutdown(sockfd, 2); There's nothing async going on and at the end both send and receive queues are empty (as reported by netstat). Connections last only ~20ms. All clients behave the same way, are the same implementation, etc. Now let's say I'm accepting X connections from client 1 and another X from client 2. Processes still report that they're idle all the time. If I add another X connections from client 3, suddenly the server processes start hanging just after accepting. The first blocking thing they do after accept(); is while (<$clt>) ... - but they don't get any data (on the first try already). Suddenly all 10 processes are in this state and do not stop waiting. On strace, the server processes seem to hang on read(), which makes sense. There are loads of connections in TIME_WAIT state belonging to that server (~100 when the problem starts to manifest), but this might be a red herring. What could be happening here?

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• what use does the javascript forEach method have (that map can't do)?

  - by JohnMerlino

  Hey all, The only difference I see in map and foreach is that map is returning an array and foreach is not. However, I don't even understand the last line of the foreach method "func.call(scope, this[i], i, this);". For example, isn't "this" and "scope" referring to same object and isn't this[i] and i referring to the current value in the loop? I noticed on another post someone said "Use forEach when you want to do something on the basis of each element of the list. You might be adding things to the page, for example. Essentially, it's great for when you want "side effects". I don't know what is meant by side effects. Array.prototype.map = function(fnc) { var a = new Array(this.length); for (var i = 0; i < this.length; i++) { a[i] = fnc(this[i]); } return a; } Array.prototype.forEach = function(func, scope) { scope = scope || this; for (var i = 0, l = this.length; i < l; i++) func.call(scope, this[i], i, this); } Finally, are there any real uses for these methods in javascript (since we aren't updating a database) other than to manipulate numbers like this: alert([1,2,3,4].map(function(x){ return x + 1})); //this is the only example I ever see of map in javascript. Thanks for any reply.

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• How to create closed areas (convex polygons) from set of line segments ?

  - by Marten

  The following problem is in 2D, so some simplifications can be made when suggesting answers. I need to create closed areas (defined either by line segments or just set of points - convex polygon) from a set of points/line segments. Basically I used Voronoi to generate "roads". Then I changed some of the data. Now I need a way to loop through that data (which is still line segments but doesn't comply with Voronoi anymore) and generate "neigbourhoods" that are bordered with the "roads". I looked at some graph diagrams and shortest path theories, but I could not figure it out. Logically it could be done by starting at left edge from one point, finding the way back to that point using the shortest path with available lines (using only clockwise directions). Then mark this line set down and remove from the data. Then you can repeat the same process and get all the areas like that. I tried to implement that but it did not get me anywhere as I could not figure out a way to write a C++ code that could do that. Problem was with choosing the most counterclockwise line from available lines from a specific point. All angle based math I did gave wrong answers because the way sin/cos are implemented in c++. So to summarize - if you can help me with a totally new approach to the problem its good, if not could you help me find a way to write the part of the code that finds the shortest clockwise path back to the beginning point using the line segment set as paths back. Thank you for your help!

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• Program repeats each time a character is scanned .. How to stop it ?

  - by ZaZu

  Hello there, I have a program that has this code : #include<stdio.h> main(){ int input; char g; do{ printf("Choose a numeric value"); printf(">"); scanf("\n%c",&input); g=input-'0'; }while((g>=-16 && g<=-1)||(g>=10 && g<=42)||(g>=43 && g<=79)); } It basically uses ASCII manipulation to allow the program to accept numbers only .. '0' is given the value 48 by default...the ASCII value - 48 gives a ranges of numbers above (in the while statement) Anyway, whenever a user inputs numbers AND alphabets, such as : abr39293afakvmienb23 The program ignores : a,b,r .. But takes '3' as the first input. For a b and r, the code under the do loop repeats. So for the above example, I get : Choose a numeric value >Choose a numeric value> Choose a numeric value >3 Is there a way I can stop this ??? I tried using \n%c to scan the character and account for whitespace, but that didnt work :( Please help thank you very much !

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