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• Measuring execution time of selected loops

  - by user95281

  I want to measure the running times of selected loops in a C program so as to see what percentage of the total time for executing the program (on linux) is spent in these loops. I should be able to specify the loops for which the performance should be measured. I have tried out several tools (vtune, hpctoolkit, oprofile) in the last few days and none of them seem to do this. They all find the performance bottlenecks and just show the time for those. Thats because these tools only store the time taken that is above a threshold (~1ms). So if one loop takes lesser time than that then its execution time won't be reported. The basic block counting feature of gprof depends on a feature in older compilers thats not supported now. I could manually write a simple timer using gettimeofday or something like that but for some cases it won't give accurate results. For ex: for (i = 0; i < 1000; ++i) { for (j = 0; j < N; ++j) { //do some work here } } Now here I want to measure the total time spent in the inner loop and I will have to put a call to gettimeofday inside the first loop. So gettimeofday itself will get called a 1000 times which introduces its own overhead and the result will be inaccurate.

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• puzzled with java if else performance

  - by user1906966

  I am doing an investigation on a method's performance and finally identified the overhead was caused by the "else" portion of the if else statement. I have written a small program to illustrate the performance difference even when the else portion of the code never gets executed: public class TestIfPerf { public static void main( String[] args ) { boolean condition = true; long time = 0L; int value = 0; // warm up test for( int count=0; count<10000000; count++ ) { if ( condition ) { value = 1 + 2; } else { value = 1 + 3; } } // benchmark if condition only time = System.nanoTime(); for( int count=0; count<10000000; count++ ) { if ( condition ) { value = 1 + 2; } } time = System.nanoTime() - time; System.out.println( "1) performance " + time ); time = System.nanoTime(); // benchmark if else condition for( int count=0; count<10000000; count++ ) { if ( condition ) { value = 1 + 2; } else { value = 1 + 3; } } time = System.nanoTime() - time; System.out.println( "2) performance " + time ); } } and run the test program with java -classpath . -Dmx=800m -Dms=800m TestIfPerf. I performed this on both Mac and Linux Java with 1.6 latest build. Consistently the first benchmark, without the else is much faster than the second benchmark with the else section even though the code is structured such that the else portion is never executed because of the condition. I understand that to some, the difference might not be significant but the relative performance difference is large. I wonder if anyone has any insight to this (or maybe there is something I did incorrectly). Linux benchmark (in nano) performance 1215488 performance 2629531 Mac benchmark (in nano) performance 1667000 performance 4208000

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• DSA signature verification input

  - by calccrypto

  What is the data inputted into DSA when PGP signs a message? From RFC4880, i found A Signature packet describes a binding between some public key and some data. The most common signatures are a signature of a file or a block of text, and a signature that is a certification of a User ID. im not sure if it is the entire public key, just the public key packet, or some other derivative of a pgp key packet. whatever it is, i cannot get the DSA signature to verify here is a sample im testing my program on: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 abcd -----BEGIN PGP SIGNATURE----- Version: BCPG v1.39 iFkEARECABkFAk0z65ESHGFiYyAodGVzdCBrZXkpIDw+AAoJEC3Jkh8+bnkusO0A oKG+HPF2Qrsth2zS9pK+eSCBSypOAKDBgC2Z0vf2EgLiiNMk8Bxpq68NkQ== =gq0e -----END PGP SIGNATURE----- Dumped from pgpdump.net Old: Signature Packet(tag 2)(89 bytes) Ver 4 - new Sig type - Signature of a canonical text document(0x01). Pub alg - DSA Digital Signature Algorithm(pub 17) Hash alg - SHA1(hash 2) Hashed Sub: signature creation time(sub 2)(4 bytes) Time - Mon Jan 17 07:11:13 UTC 2011 Hashed Sub: signer's User ID(sub 28)(17 bytes) User ID - abc (test key) <> Sub: issuer key ID(sub 16)(8 bytes) Key ID - 0x2DC9921F3E6E792E Hash left 2 bytes - b0 ed DSA r(160 bits) - a1 be 1c f1 76 42 bb 2d 87 6c d2 f6 92 be 79 20 81 4b 2a 4e DSA s(160 bits) - c1 80 2d 99 d2 f7 f6 12 02 e2 88 d3 24 f0 1c 69 ab af 0d 91 -> hash(DSA q bits) and the public key for it is: -----BEGIN PGP PUBLIC KEY BLOCK----- Version: BCPG v1.39 mOIETTPqeBECALx+i9PIc4MB2DYXeqsWUav2cUtMU1N0inmFHSF/2x0d9IWEpVzE kRc30PvmEHI1faQit7NepnHkkphrXLAoZukAoNP3PB8NRQ6lRF6/6e8siUgJtmPL Af9IZOv4PI51gg6ICLKzNO9i3bcUx4yeG2vjMOUAvsLkhSTWob0RxWppo6Pn6MOg dMQHIM5sDH0xGN0dOezzt/imAf9St2B0HQXVfAAbveXBeRoO7jj/qcGx6hWmsKUr BVzdQhBk7Sku6C2KlMtkbtzd1fj8DtnrT8XOPKGp7/Y7ASzRtBFhYmMgKHRlc3Qg a2V5KSA8PohGBBMRAgAGBQJNM+p5AAoJEC3Jkh8+bnkuNEoAnj2QnqGtdlTgUXCQ Fyvwk5wiLGPfAJ4jTGTL62nWzsgrCDIMIfEG2shm8bjMBE0z6ngQAgCUlP7AlfO4 XuKGVCs4NvyBpd0KA0m0wjndOHRNSIz44x24vLfTO0GrueWjPMqRRLHO8zLJS/BX O/BHo6ypjN87Af0VPV1hcq20MEW2iujh3hBwthNwBWhtKdPXOndJGZaB7lshLJuW v9z6WyDNXj/SBEiV1gnPm0ELeg8Syhy5pCjMAgCFEc+NkCzcUOJkVpgLpk+VLwrJ /Wi9q+yCihaJ4EEFt/7vzqmrooXWz2vMugD1C+llN6HkCHTnuMH07/E/2dzciEYE GBECAAYFAk0z6nkACgkQLcmSHz5ueS7NTwCdED1P9NhgR2LqwyS+AEyqlQ0d5joA oK9xPUzjg4FlB+1QTHoOhuokxxyN =CTgL -----END PGP PUBLIC KEY BLOCK----- the public key packet of the key is mOIETTPqeBECALx+i9PIc4MB2DYXeqsWUav2cUtMU1N0inmFHSF/2x0d9IWEpVzEkRc30PvmEHI1faQi t7NepnHkkphrXLAoZukAoNP3PB8NRQ6lRF6/6e8siUgJtmPLAf9IZOv4PI51gg6ICLKzNO9i3bcUx4ye G2vjMOUAvsLkhSTWob0RxWppo6Pn6MOgdMQHIM5sDH0xGN0dOezzt/imAf9St2B0HQXVfAAbveXBeRoO 7jj/qcGx6hWmsKUrBVzdQhBk7Sku6C2KlMtkbtzd1fj8DtnrT8XOPKGp7/Y7ASzR in radix 64 i have tried many different combinations of sha1(< some data + 'abcd'),but the calculated value v never equals r, of the signature i know that the pgp implementation i used to create the key and signature is correct. i also know that my DSA implementation and PGP key data extraction program are correct. thus, the only thing left is the data to hash. what is the correct data to be hashed?

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• Creating and using a static lib in xcode

  - by Alasdair Morrison

  I am trying to create a static library in xcode and link to that static library from another program. So as a test i have created a BSD static C library project and just added the following code: //Test.h int testFunction(); //Test.cpp #include "Test.h" int testFunction() { return 12; } This compiles fine and create a .a file (libTest.a). Now i want to use it in another program so I create a new xcode project (cocoa application) Have the following code: //main.cpp #include <iostream> #include "Testlib.h" int main (int argc, char * const argv[]) { // insert code here... std::cout << "Result:\n" <<testFunction(); return 0; } //Testlib.h extern int testFunction(); I right clicked on the project - add - existing framework - add other Selected the .a file and it added it into the project view. I always get this linker error: Build TestUselibrary of project TestUselibrary with configuration Debug Ld build/Debug/TestUselibrary normal x86_64 cd /Users/myname/location/TestUselibrary setenv MACOSX_DEPLOYMENT_TARGET 10.6 /Developer/usr/bin/g++-4.2 -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk -L/Users/myname/location/TestUselibrary/build/Debug -L/Users/myname/location/TestUselibrary/../Test/build/Debug -F/Users/myname/location/TestUselibrary/build/Debug -filelist /Users/myname/location/TestUselibrary/build/TestUselibrary.build/Debug/TestUselibrary.build/Objects-normal/x86_64/TestUselibrary.LinkFileList -mmacosx-version-min=10.6 -lTest -o /Users/myname/location/TestUselibrary/build/Debug/TestUselibrary Undefined symbols: "testFunction()", referenced from: _main in main.o ld: symbol(s) not found collect2: ld returned 1 exit status I am new to macosx development and fairly new to c++. I am probably missing something fairly obvious, all my experience comes from creating dlls on the windows platform. I really appreciate any help.

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• Reusing Windows Picture and Fax Viewer process to load a new image from FileSystemWatcher

  - by Cory Larson

  So for an idea for my birthday party I'm setting up a photo booth. I've got software to remotely control the camera and all that, but I need to write a little application to monitor the folder where the pictures get saved and display them. Here's what I've got so far. The issue is that I don't want to launch a new Windows Photo Viewer process every time the FileSystemWatcher sees a new file, I just want to load the latest image into the current instance of the Windows Photo Viewer (or start a new one if one isn't running). class Program { static void Main(string[] args) { new Program().StartWatching(); } public void StartWatching() { FileSystemWatcher incoming = new FileSystemWatcher(); incoming.Path = @"G:\TempPhotos\"; incoming.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.FileName; incoming.Filter = "*.jpg"; incoming.Created += new FileSystemEventHandler(ShowImage); incoming.EnableRaisingEvents = true; Console.WriteLine("Press \'q\' to quit."); while (Console.Read() != 'q') ; } private void ShowImage(object source, FileSystemEventArgs e) { string s1 = Environment.ExpandEnvironmentVariables("%windir%\\system32\\rundll32.exe "); string s2 = Environment.ExpandEnvironmentVariables("%windir%\\system32\\shimgvw.dll,ImageView_Fullscreen " + e.FullPath); Process.Start(s1, s2); Console.WriteLine("{0} : Image \"{0}\" at {1:t}.", e.ChangeType, e.FullPath, DateTime.Now); } } If you don't have a tried and true solution, a simple push in the right direction would be just as valuable. And FYI, this will be running on a 64-bit Windows 7 machine. Thanks!

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• Alright, I'm still stuck on this homework problem. C++

  - by Josh

  Okay, the past few days I have been trying to get some input on my programs. Well I decided to scrap them for the most part and try again. So once again, I'm in need of help. For the first program I'm trying to fix, it needs to show the sum of SEVEN numbers. Well, I'm trying to change is so that I don't need the mem[##] = ####. I just want the user to be able to input the numbers and the program run from there and go through my switch loop. And have some kind of display..saying like the sum is?.. Here's my code so far. #include <iostream> #include <iomanip> #include <ios> using namespace std; int main() { const int READ = 10; const int WRITE = 11; const int LOAD = 20; const int STORE = 21; const int ADD = 30; const int SUBTRACT = 31; const int DIVIDE = 32; const int MULTIPLY = 33; const int BRANCH = 40; const int BRANCHNEG = 41; const int BRANCHZERO = 42; const int HALT = 43; int mem[100] = {0}; //Making it 100, since simpletron contains a 100 word mem. int operation; //taking the rest of these variables straight out of the book seeing as how they were italisized. int operand; int accum = 0; // the special register is starting at 0 int counter; for ( counter=0; counter < 100; counter++) mem[counter] = 0; // This is for part a, it will take in positive variables in //a sent-controlled loop and compute + print their sum. Variables from example in text. mem[0] = 1009; mem[1] = 1109; mem[2] = 2010; mem[3] = 2111; mem[4] = 2011; mem[5] = 3100; mem[6] = 2113; mem[7] = 1113; mem[8] = 4300; counter = 0; //Makes the variable counter start at 0. while(true) { operand = mem[ counter ]%100; // Finds the op codes from the limit on the mem (100) operation = mem[ counter ]/100; //using a switch loop to set up the loops for the cases switch ( operation ){ case READ: //reads a variable into a word from loc. Enter in -1 to exit cout <<"\n Input a positive variable: "; cin >> mem[ operand ]; counter++; break; case WRITE: // takes a word from location cout << "\n\nThe content at location " << operand << " is " << mem[operand]; counter++; break; case LOAD:// loads accum = mem[ operand ];counter++; break; case STORE: //stores mem[ operand ] = accum;counter++; break; case ADD: //adds accum += mem[operand];counter++; break; case SUBTRACT: // subtracts accum-= mem[ operand ];counter++; break; case DIVIDE: //divides accum /=(mem[ operand ]);counter++; break; case MULTIPLY: // multiplies accum*= mem [ operand ];counter++; break; case BRANCH: // Branches to location counter = operand; break; case BRANCHNEG: //branches if acc. is < 0 if (accum < 0) counter = operand; else counter++; break; case BRANCHZERO: //branches if acc = 0 if (accum == 0) counter = operand; else counter++; break; case HALT: // Program ends break; } } return 0; } part B int main() { const int READ = 10; const int WRITE = 11; const int LOAD = 20; const int STORE = 21; const int ADD = 30; const int SUBTRACT = 31; const int DIVIDE = 32; const int MULTIPLY = 33; const int BRANCH = 40; const int BRANCHNEG = 41; const int BRANCHZERO = 41; const int HALT = 43; int mem[100] = {0}; int operation; int operand; int accum = 0; int pos = 0; int j; mem[22] = 7; // loop 7 times mem[25] = 1; // increment by 1 mem[00] = 4306; mem[01] = 2303; mem[02] = 3402; mem[03] = 6410; mem[04] = 3412; mem[05] = 2111; mem[06] = 2002; mem[07] = 2312; mem[08] = 4210; mem[09] = 2109; mem[10] = 4001; mem[11] = 2015; mem[12] = 3212; mem[13] = 2116; mem[14] = 1101; mem[15] = 1116; mem[16] = 4300; j = 0; while ( true ) { operand = memory[ j ]%100; // Finds the op codes from the limit on the memory (100) operation = memory[ j ]/100; //using a switch loop to set up the loops for the cases switch ( operation ){ case 1: //reads a variable into a word from loc. Enter in -1 to exit cout <<"\n enter #: "; cin >> memory[ operand ]; break; case 2: // takes a word from location cout << "\n\nThe content at location " << operand << "is " << memory[operand]; break; case 3:// loads accum = memory[ operand ]; break; case 4: //stores memory[ operand ] = accum; break; case 5: //adds accum += mem[operand];; break; case 6: // subtracts accum-= memory[ operand ]; break; case 7: //divides accum /=(memory[ operand ]); break; case 8: // multiplies accum*= memory [ operand ]; break; case 9: // Branches to location j = operand; break; case 10: //branches if acc. is < 0 break; case 11: //branches if acc = 0 if (accum == 0) j = operand; break; case 12: // Program ends exit(0); break; } j++; } return 0; }

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• Compiling and using NTL c++ library for Windows

  - by Martin Lauridsen

  Hi there, I have compiled the NTL inifite precision integer arithmetic library for c++, using Microsoft Visual Studio 2008. I did as explained, on this site, using the Visual Studio interface, rather than from the command prompt. Actually I would rather do it from the command prompt, but I was not sure how to. Anyhow, I got the library compiled, and I now want to compile a program using the library, from the command prompt. The program I am trying to compile, has been tested on a linux system, where I compile it with the following c++ -I/appl/htopopt/Linux_x86_64/NTL-5.4.2/include mpqs.cpp main.cpp -o main -L/appl/htopopt/Linux_x86_64/NTL-5.4.2/lib -lntl -L/appl/htopopt/Linux_x86_64/gmp-4.2.1/lib -lgmp -lm Nevermind the gmp stuff, I dont have that installed on Windows. It is purely an optional thing that will make the NTL run faster. Anyhow, this works fine on linux. Now on Windows I write the following cl /EHsc /I D:\Downloads\WinNTL-5_5_2\include mpqs.cpp main.cpp /link /LIBPATH:"D:\Documents\Visual Studio 2008\Projects\ntl\Debug" But this results in the following errors: mpqs.cpp mpqs.cpp(38) : error C2039: 'find_smooth_vals' : is not a member of 'QS' d:\desktop\qs\mpqs.h(12) : see declaration of 'QS' mpqs.cpp(41) : error C2065: 'M' : undeclared identifier mpqs.cpp(41) : error C2065: 'n' : undeclared identifier mpqs.cpp(42) : error C2065: 'sieve_table' : undeclared identifier mpqs.cpp(42) : error C2228: left of '.size' must have class/struct/union type is ''unknown-type'' mpqs.cpp(43) : error C2065: 'sieve_table' : undeclared identifier mpqs.cpp(44) : error C2065: 'qx_table' : undeclared identifier mpqs.cpp(44) : error C3861: 'test_smoothness': identifier not found mpqs.cpp(45) : error C2065: 'smooth_indices' : undeclared identifier mpqs.cpp(45) : error C2228: left of '.push_back' must have class/struct/union type is ''unknown-type'' main.cpp Generating Code... It is as if, my mpqs.h file is not included into the compilation process? Also I dont understand why it complains about .push_back() for a vector type? Help is much appreciated!

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• Running multiple applications in STM32 flash

  - by Richard

  Hey! I would like to have two applications in my STM32 flash, one is basically a boot and the other the 'main' application. I have figured out how to load each of them into different areas of flash, and after taking a memory dump everything looks like it is in the right place. So when I do a reset it loads the boot, all the boot does at the moment is jump to the application. Debugging the boot, this all appears to work correctly. However the problems arrives after i've made the jump to the application, it just executes one instruction (assembly) and then jumps back to the boot. It should stay in the application indefinitely. My question is then, where should I 'jump' to in the app? It seems that there are a few potential spots, such as the interrupt vectors, the reset handler, the main function of the app. Actually I've tried all of those with no success. Hopefully that makes sense, i'll update the question if not. thanks for your help! Richard Updates: I had a play around in the debugger and manually changed the program counter to the main of the application, and well that worked a charm, so it makes me think there is something wrong with my jump, why doesn't the program counter keep going after the jump? Actually it seems to be the PSR, the 'T' gets reset on the jump, if I set that again after the jump it continues on with the app as I desire Ok found a solution, seems that you need to have the PC LSB set to 1 when you do a branch or it falls into the 'ARM' mode (32 bit instruction instead of 16 bit instructions like in the 'thumb' mode. Quite an obscure little problem, thanks for letting me share it with you!

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• reading excel using scriptom for groovy, producing xml

  - by john

  Dear friends, I got a program from http://kousenit.wordpress.com/2007/03/27/groovyness-with-excel-and-xml but I got some very strange results: 1) I can still print xml but two records are not readable. 2) I got exception suggesting some thing missing could some experts enlighten me about what might go wrong? I copied the program and result below. thanks! import org.codehaus.groovy.scriptom.ActiveXObject def addresses = new File('addresses1.xls').canonicalPath def xls = new ActiveXObject('Excel.Application') def workbooks = xls.Workbooks def workbook = workbooks.Open(addresses) // select the active sheet def sheet = workbook.ActiveSheet sheet.Visible = true // get the XML builder ready def builder = new groovy.xml.MarkupBuilder() builder.people { for (row in 2..1000) { def ID = sheet.Range("A${row}").Value.value if (!ID) break // use the builder to write out each person person (id: ID) { name { firstName sheet.Range("B${row}").Value.value lastName sheet.Range("C${row}").Value.value } address { street sheet.Range("D${row}").Value.value city sheet.Range("E${row}").Value.value state sheet.Range("F${row}").Value.value zip sheet.Range("G${row}").Value.value } } } } // close the workbook without asking for saving the file workbook.Close(false, null, false) // quits excel xls.Quit() xls.release() however, i got the following results: <people> <person id='1234.0'> <name> <firstName>[C@128a25</firstName> <lastName>[C@5e45</lastName> </name> <address> <street>[C@179ef7c</street> <city>[C@12f95de</city> <state>[C@138b554</state> <zip>12345.0</zip> </address> </person> </person> Exception thrown May 12, 2010 4:07:15 AM org.codehaus.groovy.runtime.StackTraceUtils sanitize WARNING: Sanitizing stacktrace: java.lang.NullPointerException at org.codehaus.groovy.runtime.callsite.GetEffectivePojoFieldSite.acceptGetProperty(GetEffectivePojoFieldSite.java:43) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGetProperty(AbstractCallSite.java:237) at sriptom4_excel$_run_closure1.doCall(sriptom4_excel.groovy:18) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [1]: http://kousenit.wordpress.com/2007/03/27/groovyness-with-excel-and-xml/

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• How to properly force a Blackberry Java application to install using Loader.exe

  - by Kevin White

  I want to include the Application Loader process in a software installation, to ensure that users get our software installed on their Blackberry by the time our installer software finishes. I know this is possible, because Aerize Card Loader (http://aerize.com/blackberry/software/loader/) does this. When you install their software, if your Blackberry is connected the Application Loader will come up and force the .COD file to install to the device. I can't make it work. Looking at RIM's own documentation, I need to: Place the ALX and COD files into a subfolder here: C:\Program Files\Common Files\Research In Motion\Shared\Applications\ Add a path to the ALX file in HKCU\Software\Research In Motion\Blackberry\Loader\Packages Index the application, by executing this at the command line: loader.exe /index Start the force load, by doing this: loader.exe /defaultUSB /forceload When I execute that last command, the Application Loader comes up and says that all applications are up to date and nothing needs to be done. If I execute loader.exe by double-clicking on it (or typing in the command with no parameters), I get the regular Application Loader wizard. It shows my program as listed, but un-checked. If I check it and click next, it will install to the Blackberry. (This is the part that I want to avoid, and that Aerize Card Loader's install process avoids.) What am I missing? It appears that the Aerize installer is doing something different but I haven't been able to ascertain what.

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• Core Data - How to check if a managed object's properties have been deallocated?

  - by georryan

  I've created a program that uses core data and it works beautifully. I've since attempted to move all my core data methods calls and fetch routines into a class that is self contained. My main program then instantiates that class and makes some basic method calls into that class, and the class then does all the core data stuff behind the scenes. What I'm running into, is that sometimes I'll find that when I grab a managed object from the context, I'll have a valid object, but its properties have been deallocated, and I'll cause a crash. I've played with the zombies and looked for memory leaks, and what I have gathered is it seems that the run loop is probably responsible for deallocating the memory, but I'm not sure. Is there a way to determine if that memory has been deallocated and force the core data to get it back if I need to access it? My managedObjectContext never gets deallocated, and the fetchedResultsController never does, either. I thought maybe I needed to use the [managedObjectContext refreshObject:mergeData:] method, or the [managedObjectContext setRetainsRegisteredObjects:] method. Although, I'm under the impression that last one may not be the best bet since it will be more memory intensive (from what I understand). These errors only popped up when I moved the core data calls into another class file, and they are random when they show up. Any insight would be appreciated. -Ryan

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• Windows Form color changing

  - by Sef

  Hello, So i am attempting to make a MasterMind program as sort of exercise. Field of 40 picture boxes (line of 4, 10 rows) 6 buttons (red, green, orange, yellow, blue, purple) When i press one of these buttons (lets assume the red one) then a picture box turns red. My question is how do i iterate trough all these picture boxes? I can get it to work but only if i write : And this is offcourse no way to write this, would take me countless of lines that contain basicly the same. private void picRood_Click(object sender, EventArgs e) { UpdateDisplay(); pb1.BackColor = System.Drawing.Color.Red; } Press the red button - first picture box turns red Press the blue button - second picture box turns blue Press the orange button - third picture box turns orange And so on... Ive had a previous similar program that simulates a traffic light, there i could assign a value to each color (red 0, orange 1, green 2). Is something similar needed or how exactly do i adress all those picture boxes and make them correspond to the proper button. Best Regards.

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• C++ stack for multiple data types (RPN vector calculator)

  - by Arrieta

  Hello: I have designed a quick and basic vector arithmetic library in C++. I call the program from the command line when I need a rapid cross product, or angle between vectors. I don't use Matlab or Octave or related, because the startup time is larger than the computation time. Again, this is for very basic operations. I am extending this program, and I will make it work as an RPN calculator, for operations of the type: 1 2 3 4 5 6 x out: -3 6 -3 (give one vector, another vector, and the "cross" operator; spit out the cross product) The stack must accept 3d vectors or scalars, for operations like: 1 2 3 2 * out: 2 4 6 The lexer and parser for this mini-calculator are trivial, but I cannot seem to think of a good way for creating the internal stack. How would you create a stack of for containing vectors or doubles (I rolled up my own very simple vector class - less than one hundred lines and it does everything I need). How can I create a simple stack which accepts elements of class Vector or type double? Thank you.

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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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• How to get levels for Fry Graph readability formula?

  - by Vic

  Hi, I'm working in an application (C#) that applies some readability formulas to a text, like Gunning-Fog, Precise SMOG, Flesh-Kincaid. Now, I need to implement the Fry-based Grade formula in my program, I understand the formula's logic, pretty much you take 3 100-words samples and calculate the average on sentences per 100-words and syllables per 100-words, and then, you use a graph to plot the values. Here is a more detailed explanation on how this formula works. I already have the averages, but I have no idea on how can I tell my program to "go check the graph and plot the values and give me a level." I don't have to show the graph to the user, I only have to show him the level. I was thinking that maybe I can have all the values in memory, divided into levels, for example: Level 1: values whose sentence average are between 10.0 and 25+, and whose syllables average are between 108 and 132. Level 2: values whose sentence average are between 7.7 and 10.0, and .... so on But the problem is that so far, the only place in which I have found the values that define a level, are in the graph itself, and they aren't too much accurate, so if I apply the approach commented above, trying to take the values from the graph, my level estimations would be too much imprecise, thus, the Fry-based Grade will not be accurate. So, maybe any of you knows about some place where I can find exact values for the different levels of the Fry-based Grade, or maybe any of you can help me think in a way to workaround this. Thanks

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• Calling unmanaged code from within C#

  - by Charles Gargent

  I am trying to use a dll in my c# program but I just cant seem to get it to work. I have made a test app shown below. The return value is 0, however it does not actually do what it is supposed to do. Whereas the following command does work: rundll32 cmproxy.dll,SetProxy /source_filename proxy-1.txt /backup_filename roxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /Profile "C:\Documents and ettings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp" Code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Security.Cryptography; using System.Runtime.InteropServices; using System.Net; using WUApiLib; namespace nac { class Program { [DllImport("cmproxy.dll", CharSet = CharSet.Unicode)] static extern int SetProxy(string cmdLine); static void Main(string[] args) { string cmdLine = @"/source_filename proxy-1.txt /backup_filename proxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /Profile ""C:\Documents and Settings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp"""; Console.WriteLine(SetProxy(cmdLine)); } } } Here is the contents of the dumpbin /exports command File Type: DLL Section contains the following exports for cmproxy.dll 00000000 characteristics 3E7FEF8C time date stamp Tue Mar 25 05:56:28 2003 0.00 version 1 ordinal base 1 number of functions 1 number of names ordinal hint RVA name 1 0 00001B68 SetProxy Summary 1000 .data 1000 .reloc 1000 .rsrc 2000 .text When this works it sets the proxy server for a VPN connection.

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• ANTLR Tree Grammar and StringTemplate Code Translation

  - by Behrooz Nobakht

  I am working on a code translation project with a sample ANTLR tree grammar as: start: ^(PROGRAM declaration+) -> program_decl_tmpl(); declaration: class_decl | interface_decl; class_decl: ^(CLASS ^(ID CLASS_IDENTIFIER)) -> class_decl_tmpl(cid={$CLASS_IDENTIFIER.text}); The group template file for it looks like: group My; program_decl_tmpl() ::= << *WHAT?* >> class_decl_tmpl(cid) ::= << public class <cid> {} >> Based on this, I have these questions: Everything works fine apart from that what I should express in WHAT? to say that a program is simply a list of class declarations to get the final generated output? Is this approach averagely suitable for not so a high-level language? I have also studied ANTLR Code Translation with String Templates, but it seems that this approach takes much advantage of interleaving code in tree grammar. Is it also possible to do it as much as possible just in String Templates?

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• How do I disable the network connection from .Net without needing admin priveledges?

  - by Brad Mathews

  I may be SOL on this but I thought I would give throw it out for possible solutions. I am writing a computer access control service to help me control my kids' computer use. Plan on open sourcing it when I have it working. It is written in VB.Net and needs to work on XP through 7. I am running into all sorts of security and desktop access issues on Windows 7. The service needs to run as admin to execute the NetSh command to disable the network. But I cannot interact with the desktop from the service so I IPC to a UI to handle other stuff, but I still cannot detect from the service if the desktop is locked. Argghh! I could get it all working from a hidden windows form app if I could just lick the one piece that needs admin permissions: disabling the network. It does no good if a kid logs on and denies the popup asking if the program should run as administrator and he says no. Also windows 7 will not start a program set to run as admin using HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run Anyone know how to get this working? Or have an outside the box solution? Thanks! Brad

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• how do I make a portable isnan/isinf function.

  - by monkeyking

  I've been using isinf,isnan functions on linux platforms which worked perfectly. But this didn't work on osx, so I decided to use std::isinf std::isnan which works on both linux and osx. But the intel compiler doesn't recognize it, and I guess its a bug in the intel compiler according to http://software.intel.com/en-us/forums/showthread.php?t=64188 So now I just want to avoid the hassle and define my own isinf,isnan implementation. Does anyone know how this could be done Thanks edit: I ended up doing this in my sourcecode for making isinf/isnan working #include <iostream> #include <cmath> #ifdef __INTEL_COMPILER #include <mathimf.h> #endif int isnan_local(double x) { #ifdef __INTEL_COMPILER return isnan(x); #else return std::isnan(x); #endif } int isinf_local(double x) { #ifdef __INTEL_COMPILER return isinf(x); #else return std::isinf(x); #endif } int myChk(double a){ std::cerr<<"val is: "<<a <<"\t"; if(isnan_local(a)) std::cerr<<"program says isnan"; if(isinf_local(a)) std::cerr<<"program says isinf"; std::cerr<<"\n"; return 0; } int main(){ double a = 0; myChk(a); myChk(log(a)); myChk(-log(a)); myChk(0/log(a)); myChk(log(a)/log(a)); return 0; }

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• C# WebClient OpenRead url

  - by Octopus-Paul

  So i have this program that fetch a page using a short link (I used Google url shortener) to build my example i used the code from Using WebClient in C# is there a way to get the URL of a site after being redirected? using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; using System.Net; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { MyWebClient client = new MyWebClient(); client.OpenRead("http://tinyurl.com/345yj7x"); Uri uri = client.ResponseUri; Console.WriteLine(uri.AbsoluteUri); Console.Read(); } } class MyWebClient : WebClient { Uri _responseUri; public Uri ResponseUri { get { return _responseUri; } } protected override WebResponse GetWebResponse(WebRequest request) { WebResponse response = base.GetWebResponse(request); _responseUri = response.ResponseUri; return response; } } } I do not understant a thing: when i do client.OpenRead("http://tinyurl.com/345yj7x"); this downloads the page that the url points to? If this method downloads the page, I need something to get me only the url, so if there a method to get only some headers, or only the url please let me know.

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• Python print statement prints nothing with a carriage return

  - by Jonathan Sternberg

  I'm trying to write a simple tool that reads files from disc, does some image processing, and returns the result of the algorithm. Since the program can sometimes take awhile, I like to have a progress bar so I know where it is in the program. And since I don't like to clutter up my command line and I'm on a Unix platform, I wanted to use the '\r' character to print the progress bar on only one line. But when I have this code here, it prints nothing. # Files is a list with the filenames for i, f in enumerate(files): print '\r%d / %d' % (i, len(files)), # Code that takes a long time I have also tried: print '\r', i, '/', len(files), Now just to make sure this worked in python, I tried this: heartbeat = 1 while True: print '\rHello, world', heartbeat, heartbeat += 1 This code works perfectly. What's going on? My understanding of carriage returns on Linux was that it would just move the line feed character to the beginning and then I could overwrite old text that was written previously, as long as I don't print a newline anywhere. This doesn't seem to be happening though. Also, is there a better way to display a progress bar in a command line than what I'm current trying to do?

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• Fastest way to generate delimited string from 1d numpy array

  - by Abiel

  I have a program which needs to turn many large one-dimensional numpy arrays of floats into delimited strings. I am finding this operation quite slow relative to the mathematical operations in my program and am wondering if there is a way to speed it up. For example, consider the following loop, which takes 100,000 random numbers in a numpy array and joins each array into a comma-delimited string. import numpy as np x = np.random.randn(100000) for i in range(100): ",".join(map(str, x)) This loop takes about 20 seconds to complete (total, not each cycle). In contrast, consider that 100 cycles of something like elementwise multiplication (x*x) would take than one 1/10 of a second to complete. Clearly the string join operation creates a large performance bottleneck; in my actual application it will dominate total runtime. This makes me wonder, is there a faster way than ",".join(map(str, x))? Since map() is where almost all the processing time occurs, this comes down to the question of whether there a faster to way convert a very large number of numbers to strings.

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• Iterate through main function in C?

  - by Mohit Deshpande

  Here is my main function: int main(int argc, char **argv) { LoadFile(); Node *temp; char *key; switch (GetUserInput()) { case 1: temp = malloc(sizeof(Node)); printf("\nEnter the key of the new node: "); scanf("%s", temp->key); printf("\nEnter the value of the new node: "); scanf("%s", temp->value); AddNode(temp); free(temp); break; case 2: key = malloc(sizeof(char *)); printf("Enter the key of the node you want to delete: "); scanf("%s", key); DeleteNode(key); free(key); break; case 3: PrintAll(); break; case 4: SaveFile(); break; case 5: return 0; break; default: printf("\nWrong choice!\n"); break; } return 0; } The only problem with it is that after any case statement breaks, the program just exits out. I understand why, but I don't know how to fix it. I want the program to repeat itself each time even after the case statements. Would I just say: main(argc, argv); before every break statement?

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• Need help in tuning a sql-query

  - by Viper

  Hello, i need some help to boost this SQL-Statement. The execution time is around 125ms. During the runtime of my program this sql (better: equally structured sqls for different tables) will be called 300.000 times. The average row count in the tables lies around 10.000.000 rows and new rows (updates/inserts) will be added with a timestamp each day. Data which are interesting for this particular export-program lies in the last 1-3 days. Maybe this is helpful for an index to create. The data i need is the current valid row for a given id and the forerunner datarow to get the updates (if exists). We use a Oracle 11g database and Dot.Net Framework 3.5 SQL-Statement to boost: select ID_SOMETHING, -- Number(12) ID_CONTRIBUTOR, -- Char(4 Byte) DATE_VALID_FROM, -- DATE DATE_VALID_TO -- DATE from TBL_SOMETHING XID where ID_SOMETHING = :ID_INSTRUMENT and ID_CONTRIBUTOR = :ID_CONTRIBUTOR and DATE_VALID_FROM <= :EXPORT_DATE and DATE_VALID_TO >= :EXPORT_DATE order by DATE_VALID_FROM asc; Here i uploaded the current Explain-Plan for this query. I'm not a database expert so i don't know which index-type would fit best for this requirement. I have seen that there are many different possible index-types which could be applied. Maybe Oracle Optimizer Hints are helpful, too. Does anyone has a good idea for tuning this sql or can point me in a right direction?

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• Need Help with wxPython & pyGame

  - by Xavier

  Hi Guys, I'm actually in need of your help and advice here on my assignment that I am working on. First of all, I was task to do a program that runs langton's ant simulation. For that, I've managed to get the source code (from snippets.dzone.com/posts/show/5143) and edited it accordingly to my requirements. This was done and ran in pygame module extension. In addition, my task requires a GUI to interface for users to run and navigate through the screens effectively with the langton's ant program running. I used wxPython with the help of an IDE called BOA constructor to create the frames, buttons, textboxes, etc. Basically, all the stuff needed in the interfaces. However, I've ran into some problems listed below: Found problem integrating pyGame with wxPython. On this note, I've research the internet for answers and tutorials where I found out from website: wiki.wxpython.org/IntegratingPyGame & aspn.activestate.com/ASPN/Mail/Message/wxpython-users/3178042. I understand from the sites that integrating pyGame with wxPython will be a difficult task where it has caused common problems like the inability to placing other controls into the frames as the pyGame application will cover the entire panel. I really hope that you can clarify my doubts on this and advise me on the path that I should take from here. Therefore, I ask the following questions: Is it feasible to integrate pyGame with wxPython? If it is not feasible to integrate pyGame with wxPython, what other alternatives do I have to create a GUI interface integrating pyGame into it. If so how do I go about? If it is possible to go about integrating pyGame with wxPython, how do I go about doing so? Really need you guys opinion on this.

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