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  • Circumvent c++ null-terminated string frustration

    - by ypnos
    I'm using boost::program_options and it suffers from the same as many other c++ libs, even std itself: It still uses C-style null-terminated strings, because nobody really likes the weak std::string. The method in question is: options_description_easy_init& operator()(const char* name, const value_semantic* s, const char* description); The typical use case is just fine: options.add_options() ("graphical", bool_switch(&isGraphical)->default_value(false), "Show any graphical output during runtime") However, I need the name of the option to be set dynamically. The reason is that in some cases I nead a custom prefix, which is added to the string by my function std::string key(const std::string& k): options.add_options() (key("graphical"), bool_switch(&isGraphical)->default_value(false), "Show any graphical output during runtime") This fails. I could now use c_str() on the std::string but that's evil -- I don't know how long program_options keeps the variable around and if my string is still alive when needed. I could also reserve memory in a buffer etc. and hand in that. The buffer is never freed and it sucks/is evil. Is there anything else I can do to circumvent the C-style string mess in this situation?

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  • Know the row with max characters (C)

    - by l_core
    I have wrote a program in C, to find the row with the max number of characters. Here is the code #include <stdio.h> #include <stdlib.h> #include <ctype.h> #include <string.h> int main (int argc, char *argv[]) { char c; /* used to store the character with getc */ int c_tot = 0, c_rig = 0, c_max = 0; /* counters of characters*/ int r_tot = 0; /* counters of rows */ FILE *fptr; fptr = fopen(argv[1], "r"); if (fptr == NULL || argc != 2) { printf ("Error opening the file %s\n'", argv[1]); exit(EXIT_FAILURE); } while ( (c = getc(fptr)) != EOF) { if (c != ' ' && c != '\n') { c_tot++; c_rig++; } if (c == '\n') { r_tot++; if (c_rig > c_max) c_max = c_rig; c_rig = 0; } } printf ("Total rows: %d\n", r_tot); printf ("Total characters: %d\n", c_tot); printf ("Total characters in a row: %d\n", c_max); printf ("Average number of characters on a row: %d\n", (c_tot/r_tot)); printf ("The row with max characters is: %s\n", ??????) return 0; } I can easily find the row with the highest number of characters but how can i print that out? Thank You Folks

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  • A Question about dereferencing pointer to incomplete type In C programming

    - by user552279
    Hi, can you explain this error for me? Blockquote /////////////////////////////// In my A.h file: struct TreeNode; struct TreeHead; typedef struct TreeNode * Node; typedef struct TreeHead * Head; /////////////////////////////// In my A.c file: struct TreeNode { char* theData; Node Left; Node Right; } ; struct TreeHead{ int counter; char type; Node Root; }; Head Initialisation() { Head treeHead; treeHead = malloc(sizeof (struct TreeHead)); treeHead-Root = malloc(sizeof (struct TreeNode)); return treeHead; } /////////////////////////////// In my Main.c file: Head head; Node tree; int choose =5; head = Initialisation(); (head-Root) = tree; //When compiling, this line has an error: error: dereferencing pointer to incomplete type Blockquote haed-Root will return a Node pointer, tree is also a Node pointer. So why error is dereferencing pointer to "incomplete" type?

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  • SFINAE and detecting if a C++ function object returns void.

    - by Tom Swirly
    I've read the various authorities on this, include Dewhurst and yet haven't managed to get anywhere with this seemingly simple question. What I want to do is to call a C++ function object, (basically, anything you can call, a pure function or a class with ()), and return its value, if that is not void, or "true" otherwise. #include <stdio.h> struct Foo { void operator()() {} }; struct Bar { bool operator()() { return false; } }; Foo foo; Bar bar; bool baz() { return false; } void bang() {} const char* print(bool b) { printf(b ? "true, " : "false, "); } template <typename Functor> bool magicCallFunction(Functor f) { return true; // lots of template magic occurs here... } int main(int argc, char** argv) { print(magicCallFunction(foo)); print(magicCallFunction(bar)); print(magicCallFunction(baz)); print(magicCallFunction(bang)); printf("\n"); }

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  • How do I cover unintuitive code blocks?

    - by naivedeveloper
    For some reason, I'm having a hard time trying to cover the block of code below. This code is an excerpt from the UNIX uniq command. I'm trying to write test cases to cover all blocks, but can't seem to reach this block: if (nfiles == 2) { // Generic error routine } In context: int main (int argc, char **argv) { int optc = 0; bool posixly_correct = (getenv ("POSIXLY_CORRECT") != NULL); int nfiles = 0; char const *file[2]; file[0] = file[1] = "-"; program_name = argv[0]; skip_chars = 0; skip_fields = 0; check_chars = SIZE_MAX; for (;;) { /* Parse an operand with leading "+" as a file after "--" was seen; or if pedantic and a file was seen; or if not obsolete. */ if (optc == -1 || (posixly_correct && nfiles != 0) || ((optc = getopt_long (argc, argv, "-0123456789Dcdf:is:uw:", longopts, NULL)) == -1)) { if (optind == argc) break; if (nfiles == 2) { // Handle errors } file[nfiles++] = argv[optind++]; } else switch (optc) { case 1: { unsigned long int size; if (optarg[0] == '+' && posix2_version () < 200112 && xstrtoul (optarg, NULL, 10, &size, "") == LONGINT_OK && size <= SIZE_MAX) skip_chars = size; else if (nfiles == 2) { // Handle error } else file[nfiles++] = optarg; } break; } } } Any help would be greatly appreciated. Thanks.

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  • C++ 64bit issue

    - by Bobby
    I have the following code: tmp_data = simulated_data[index_data]; unsigned char *dem_content_buff; dem_content_buff = new unsigned char [dem_content_buff_size]; int tmp_data; unsigned long long tmp_64_data; if (!(strcmp(dems[i].GetValType(), "s32"))) { dem_content_buff[BytFldPos] = tmp_data; dem_content_buff[BytFldPos + 1] = tmp_data >> 8; dem_content_buff[BytFldPos + 2] = tmp_data >> 16; dem_content_buff[BytFldPos + 3] = tmp_data >> 24; } if (!(strcmp(dems[i].GetValType(), "f64"))) { dem_content_buff[BytFldPos] = tmp_data; dem_content_buff[BytFldPos + 1] = tmp_data >> 8; dem_content_buff[BytFldPos + 2] = tmp_data >> 16; dem_content_buff[BytFldPos + 3] = tmp_data >> 24; dem_content_buff[BytFldPos + 4] = tmp_data >> 32; dem_content_buff[BytFldPos + 5] = tmp_data >> 40; dem_content_buff[BytFldPos + 6] = tmp_data >> 48; dem_content_buff[BytFldPos + 7] = tmp_data >> 56; } I am getting some weird memory errors in other places of the application when the second if statement is true and executed. When I comment out the 2nd if statement, the problem works fine. So I suspect the way I am performing bitwise operations for 64bit data is incorrect. Can anyone see anything in this code that needs to be corrected?

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  • User switching without logging off

    - by mrh1967
    We need to switch users without logging off so we can remotely administrate a PC running with a limited user that will disconnect from the VPN if the user logs off. I've got this working by killing the explorer process and then running explorer.exe with the administrator user credentials as the following code shows: private void btnOk_Click(object sender, EventArgs e) { IntPtr tokenHandle = new IntPtr(0); if (LogonUser("administrator", Environment.UserDomainName, txtPassword.Text, 3, 0, ref tokenHandle)) { ProcessStartInfo psi = new ProcessStartInfo(@"C:\Windows\explorer.exe"); psi.UserName = "administrator"; char[] pword = txtPassword.Text.ToCharArray(); psi.Password = new System.Security.SecureString(); foreach (char c in pword) { psi.Password.AppendChar(c); } psi.UseShellExecute = false; psi.LoadUserProfile = true; restartExplorer(psi); this.Close(); } else { MessageBox.Show("Wrong password", "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); } } private void restartExplorer(ProcessStartInfo psi) { Process[] procs = System.Diagnostics.Process.GetProcesses(); foreach (Process p in procs) { if (p.ProcessName == "explorer") { p.Kill(); break; } } System.Diagnostics.Process.Start(psi); } [DllImport("advapi32.dll", SetLastError = true)] public extern static bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword, int dwLogonType, int dwLogonProvider, ref IntPtr phToken); This code and similar code that does the same but makes the ProcessStartInfo for the limited user works perfectly and allows changing between the limited and administrator accounts without disconnecting the VPN but it has one problem - If we use this to change to the administrator user, make some changes to the system, then change back to the limited user all works ok until the limited user logs off when a blank desktop is displayed until CTRL-ALT-DEL is pressed and the user is logged off again. Because we block CTRL-ALT-DEL the PC effectively hangs until it is powered off. Does anyone know how to stop this from happening so we can change users without the PC hanging when they log off?

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  • Porting Perl to C++ `print "\x{2501}" x 12;`

    - by jippie
    I am porting a program from Perl to C++ as a learning objective. I arrived at a routine that draws a table with commands like the following: Perl: print "\x{2501}" x 12; And it draws 12 times a '?' ("box drawings heavy horizontal"). Now I figured out part of the problem already: Perl: \x{}, \x00 Hexadecimal escape sequence; C++: \unnnn To print a single Unicode character: C++: printf( "\u250f\n" ); But does C++ have a smart equivalent for the 'x' operator or would it come down to a for loop? UPDATE Let me include the full source code I am trying to compile with the proposed solution. The compiler does throw an errors: g++ -Wall -Werror project.cpp -o project project.cpp: In function ‘int main(int, char**)’: project.cpp:38:3: error: ‘string’ is not a member of ‘std’ project.cpp:38:15: error: expected ‘;’ before ‘s’ project.cpp:39:3: error: ‘cout’ is not a member of ‘std’ project.cpp:39:16: error: ‘s’ was not declared in this scope #include <stdlib.h> #include <stdint.h> #include <stdio.h> #include <string.h> int main ( int argc, char *argv[] ) { if ( argc != 2 ) { fprintf( stderr , "usage: %s matrix\n", argv[0] ); exit( 2 ); } else { //std::string s(12, "\u250f" ); std::string s(12, "u" ); std::cout << s; } }

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  • Which way to store this data is effective?

    - by Tattat
    I am writing a game, which need a map, and I want to store the map. The first thing I can think of, is using a 2D-array. But the problem is what data should I store in the 2D-array. The player can tap different place to have different reaction. So, I am thinking store a 2D-array with objects, when player click some position, and I find it in the array, and use the object in that array to execute a cmd. But I have a concern that storing lots of object may use lots of memory. So, I am think storing char/int only. But it seems that not enough for me. I want to store the data like that: { Type:1 Color:Green } No matter what color is, if they are all type 1, the have same reactions in logic, but the visual effect is based on the color. So, it is not easy to store using a prue char/int data, unless I make something like this: 1-5 --> all type 1. 1=color green , 2=color red, 3 = color yellow.... ... 6-10 --> all type 2. 2 = color green, 2 = color red ... ... So, do you have any ideas on how to minimize the ram use, but also easy for me to read... ...thx

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  • Permission Denied error in IE when closing popups

    - by Kenia
    Hi everyone! I have a simple web testing application which is supposed to open and close several popups by itself (without user interaction). For this purpose i have a javascript function to access the variable where the popup reference is stored and close it if it´s not null, fairly simple. However I get random errors in IE (in FF it works as expected, all popups are closed correctly) like Message: No such interface supported Line: 86 Char: 3 Code: 0 URI: http://10.10.0.61:10000/savmailer/adm/tests/common_tests_code.js and Message: Permission denied Line: 86 Char: 3 Code: 0 URI: http://10.10.0.61:10000/savmailer/adm/tests/common_tests_code.js The line 86 references exactly the point at which I do popup.close(); in the following function function closePopupWindow(popup){ if (popup != null) { popup.close(); popup = null; } } I have googled and it seems this permission denied error is quite common to come through among IE developers, however there´s no clear solution for it, it´s just a matter of changing the code slightly "to please" IE, so to speak. However i have no idea how to change mine since it´s just 3 lines! Tried also to change the security browser settings by adding my domain to the trusted zone, but nothing, doesn't help either. If anyone has any helpful idea or notices something i might be forgetting, please, reply to this! Thanks in advance, Kenia

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  • C++, inject additional data in a method

    - by justik
    I am adding the new modul in some large library. All methods here are implemented as static. Let mi briefly describe the simplified model: typedef std::vector<double> TData; double test ( const TData &arg ) { return arg ( 0 ) * sin ( arg ( 1 ) + ...;} double ( * p_test ) ( const TData> &arg) = &test; class A { public: static T f1 (TData &input) { .... //some computations B::f2 (p_test); } }; Inside f1() some computations are perfomed and a static method B::f2 is called. The f2 method is implemented by another author and represents some simulation algorithm (example here is siplified). class B { public: static double f2 (double ( * p_test ) ( const TData &arg ) ) { //difficult algorithm working p_test many times double res = p_test(arg); } }; The f2 method has a pointer to some weight function (here p_test). But in my case some additional parameters computed in f1 for test() methods are required double test ( const TData &arg, const TData &arg2, char *arg3.... ) { } How to inject these parameters into test() (and so to f2) to avoid changing the source code of the f2 methods (that is not trivial), redesign of the library and without dirty hacks :-) ? The most simple step is to override f2 static double f2 (double ( * p_test ) ( const TData &arg ), const TData &arg2, char *arg3.... ) But what to do later? Consider, that methods are static, so there will be problems with objects. Thanks for your help.

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  • Why my linux signal handler run only once

    - by Henry Fané
    #include <iostream> #include <signal.h> #include <fenv.h> #include <string.h> void signal_handler(int sig, siginfo_t *siginfo, void* context) { std::cout << " signal_handler " << fetestexcept(FE_ALL_EXCEPT) << std::endl; throw "exception"; } void divide() { float a = 1000., b = 0., c, f = 1e-300; c = a / b; std::cout << c << " and f = " << f << std::endl; } void init_sig_hanlder() { feenableexcept(FE_ALL_EXCEPT); struct sigaction sa, initial_sa; sa.sa_sigaction = &signal_handler ; sigemptyset( &sa.sa_mask ) ; sa.sa_flags = SA_SIGINFO; // man sigaction(3) // allows for void(*)(int,siginfo_t*,void*) handler sigaction(SIGFPE, &sa, &initial_sa); } int main(int argc, char** argv) { init_sig_hanlder(); while(true) { try { sleep(1); divide(); } catch(const char * a) { std::cout << "Exception in catch: " << a << std::endl; } catch(...) { std::cout << "Exception in ..." << std::endl; } } return 0; } Produce the following results on Linux/g++4.2: signal_handler 0 Exception in catch: exception inf and f = 0 inf and f = 0 inf and f = 0 inf and f = 0 So, signal handler is executed the first time but the next fp exception does not trigger the handler again. Where am I wrong ?

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  • Why does my code fail to create a directory in "C:\Program Files" under Windows 7?

    - by sunil.nishad87
    I am using Windows 7 and I have to run one program in that windows but that program working in Windows XP. This is a Visual C++ program and I am using Visual Studio 2008 for this. When I am running my application, it does not throw any errors, but it does not create a directory in "c:\program files\". So can anyone help me to create directory and exe file? This is the code I am using: char szAppPath[MAX_PATH]; char szFileName[MAX_PATH]; DWORD dwResult; WIN32_FIND_DATA FindFileData; HANDLE hFind; dwResult = ExpandEnvironmentStrings( NULL, szAppPath, MAX_PATH); // "%ProgramFiles%" // do same for NSim directory strcat(szAppPath,"\\NSim"); hFind = FindFirstFile(szAppPath, &FindFileData); if (hFind == INVALID_HANDLE_VALUE) { //Directory Does't Exists create New if(!CreateDirectory(szAppPath,NULL)) //Throw Error { MessageBox("Unable to Create N-SIM directory","NSim Installer"); return ; } } else { //check if is directory or not if(!(FindFileData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)) { MessageBox("Can't Create N-SIM directory\n Another file with same name exists","NSim Installer"); return ; } FindClose(hFind); } //***************************************N-SIM Application**************************** strcpy(szFileName, szAppPath); HRSRC hRes; if( bRegister == FALSE) { strcat(szFileName,"\\NSim.exe"); //make same name of the Client & Server in program file hRes = FindResource(NULL, MAKEINTRESOURCE(IDR_LANSIMSERVER),RT_RCDATA); if(flagUpgrade ==0) { CString trial = installationDate(); //----- Detemine Expiry Date ----- setRegistry(trial); } }

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  • Can the size of a structure change after compiled?

    - by Sarah Altiva
    Hi, suppose you have the following structure: #include <windows.h> // BOOL is here. #include <stdio.h> typedef struct { BOOL someBool; char someCharArray[100]; int someIntValue; BOOL moreBools, anotherOne, yetAgain; char someOthercharArray[23]; int otherInt; } Test; int main(void) { printf("Structure size: %d, BOOL size: %d.\n", sizeof(Test), sizeof(BOOL)); } When I compile this piece of code in my machine (32-bit OS) the output is the following: Structure size: 148, BOOL size: 4. I would like to know if, once compiled, these values may change depending on the machine which runs the program. E.g.: if I ran this program in a 64-bit machine, would the output be the same? Or once it's compiled it'll always be the same? Thank you very much, and forgive me if the answer to this question is obvious...

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  • Segmentation Fault

    - by Biranchi
    Hi All, I have the following piece of code for getting the hostname and IP address, #include <stdlib.h> #include <stdio.h> #include <netdb.h> /* This is the header file needed for gethostbyname() */ #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> int main(int argc, char *argv[]) { struct hostent *he; if (argc!=2){ printf("Usage: %s <hostname>\n",argv[0]); exit(-1); } if ((he=gethostbyname(argv[1]))==NULL){ printf("gethostbyname() error\n"); exit(-1); } printf("Hostname : %s\n",he->h_name); /* prints the hostname */ printf("IP Address: %s\n",inet_ntoa(*((struct in_addr *)he->h_addr))); /* prints IP address */ } but i am getting a warning and segmentation fault as host.c: In function ‘main’: host.c:24: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘int’ What is the error in the code ?? Thanks

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  • C++: Simple data type for a variable in IF statement?

    - by Jason
    I am new to C++ and am making a simple text RPG, anyway, The scenario is I have a "welcome" screen with choices 1-3, and have a simple IF statement to check them, here: int choice; std::cout << "--> "; std::cin >> choice; if(choice == 1) { //.. That works fine, but if someone enters a letter as selection (instead of 1, 2 or 3) it'll become "-392493492"or something and crash the program. So I came up with: char choice; std::cout << "--> "; std::cin >> choice; if(choice == 1) { //.. This works kinda fine, but when I enter a number it seems to skip the IF statements completely.. Is the char "1" the same as the number 1? I get a compiler errro with this (ISO-CPP or something): if(choice == "1") So how on earth do I see if they entered 1-3 correctly!?

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  • GetLongPathName Undeclared

    - by iwizardpro
    When I try to compile my code with the function GetLongPathName(), the compiler tells me that the function is undeclared. I have already read the MSDN documentation located @ http://msdn.microsoft.com/en-us/library/aa364980%28VS.85%29.aspx. But, even though I included those header files, I am still getting the undeclared function error. Which header file(s) am I supposed to include when using the function? #include <Windows.h> #include <WinBase.h> #define DLLEXPORT extern "C" __declspec(dllexport) DLLEXPORT char* file_get_long(char* path_original) { long length = 0; TCHAR* buffer = NULL; if(!path_original) { return "-10"; } length = GetLongPathName(path_original, NULL, 0); if(length == 0) { return "-10"; } buffer = new TCHAR[length]; length = GetLongPathName(path_original, buffer, length); if(length == 0) { return "-10"; } return buffer; } And, if it makes a difference, I am currently compiling using Dev-C++ on a Windows Vista 64-bit.

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  • Custom Font. Keeping the font width same.

    - by user338322
    I am trying to draw a string using quartz 2d. What i am doing is, i am drawing each letter of the string individually, because each letter has special attributes associated with it, by taking each letter into a new string. The string gets printed, but the space between the letters is not uniform. It looks very ugly to read . I read someting about using custom fonts. But i have no Idea, if I can do it!! my code is here. (void) drawRect : (CGRect)rect{ NSString *string=@"My Name Is Adam"; float j=0; const char *charStr=[string cStringUsingEncoding: NSASCIIStringEncoding]; for(int i=0;i { NSString *str=[NSString stringWithFormat:@"%c",charStr[i]]; const char *s=[str cStringUsingEncoding:NSASCIIStringEncoding]; NSLog(@"%s",s); CGContextRef context=[self getMeContextRef]; CGContextSetTextMatrix (context,CGAffineTransformMakeScale(1.0, -1.0)) ; CGContextSelectFont(context, "Arial", 24, kCGEncodingMacRoman); //CGContextSetCharacterSpacing (context, 10); CGContextSetRGBFillColor (context, 0,0,200, 1); CGContextSetTextDrawingMode(context,kCGTextFill); CGContextShowTextAtPoint(context, 80+j,80,s,1); j=j+15; } } In the output 'My Name is Adam' gets printed but the space between the letters is not uniform.!! is there any way to make the space uniform!!!

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  • Working with a string as an array of characters

    - by Malfunction
    I'm having some trouble with a string represented as an array of characters. What I'd like to do, as I would do in java, is the following: while (i < chars.length) { char ch = chars[i]; if ((WORD_CHARS.indexOf(ch) >= 0) == punctuation) { String token = buffer.toString(); if (token.length() > 0) { parts.add(token); } buffer = new StringBuffer(); } buffer.append(ch); i++; } What I'm doing is something like this: while(i < strlen(chars)) { char ch = chars[i]; if(([WORD_CHARS rangeOfString:ch] >= 0) == punctuation) { NSString *token = buffer.toString(); if([token length] > 0) { [parts addObject:token]; } buffer = [NSMutableString string]; } [buffer append(ch)]; i++; } I'm not sure how I'm supposed to convert String token = buffer.toString(); to objective c, where buffer is an NSMutableString. Also, how do I check this if condition in objective c? if ((WORD_CHARS.indexOf(ch) >= 0) == punctuation) WORD_CHARS is an NSString. I'm also having trouble with appending ch to buffer. Any help is greatly appreciated.

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  • Objective-C Result from a Static Method saved to class instance variable giving "EXC_BAD_ACCESS" when used.

    - by KinGBin
    I am trying to store the md5 string as a class instance variable instead of the actual password. I have a static function that will return a md5 string which I'm trying to store in an instance variable instead of the actual password. I have the following setter for my class instance variable: -(void)setPassword:(NSString *)newpass{ if(newpass != password){ password = [utils md5HexDigest:newpass]; } } This will pass back the correct md5 string and save it to the password variable in my init function: [self setPassword:pword];. If I call another instance method and try to access self.password" I will get "EXC_BAD_ACCESS". I understand that the memory is getting released, but I have no clue to make sure it stays. I have tried alloc init with autorelease with no luck. This is the md5HexDigest function getting called during the init (graciously found in another stackoverflow question): + (NSString*)md5HexDigest:(NSString*)input { const char* str = [input UTF8String]; unsigned char result[CC_MD5_DIGEST_LENGTH]; CC_MD5(str, strlen(str), result); NSMutableString *ret = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH*2]; for(int i = 0; i<CC_MD5_DIGEST_LENGTH; i++) { [ret appendFormat:@"%02x",result[i]]; } return ret; } Any help/pointers would be greatly appreciated. I would rather have the md5 string saved in memory than the actual password calling the md5 every time I needed to use the password. Thanks in advance.

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  • How to implement tokenizer.rbegin() and rend() for boost::tokenizer ?

    - by Chan
    Hello everyone, I'm playing around with boost::tokenizer however I realize that it does not support rbegin() and rend(). I would like to ask how can I add these two functions to the existing class? This is from the boost site: #include <iostream> #include <string> #include <boost/tokenizer.hpp> using namespace std; using namespace boost; int main() { string str( "12/12/1986" ); typedef boost::tokenizer<boost::char_separator<char>> tokenizer; boost::char_separator<char> sep( "/" ); tokenizer tokens( str, sep ); cout << *tokens.begin() << endl; // cout << *tokens.rbegin() << endl; How could I implement this? return 0; }

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  • Parallelize or vectorize all-against-all operation on a large number of matrices?

    - by reve_etrange
    I have approximately 5,000 matrices with the same number of rows and varying numbers of columns (20 x ~200). Each of these matrices must be compared against every other in a dynamic programming algorithm. In this question, I asked how to perform the comparison quickly and was given an excellent answer involving a 2D convolution. Serially, iteratively applying that method, like so list = who('data_matrix_prefix*') H = cell(numel(list),numel(list)); for i=1:numel(list) for j=1:numel(list) if i ~= j eval([ 'H{i,j} = compare(' char(list(i)) ',' char(list(j)) ');']); end end end is fast for small subsets of the data (e.g. for 9 matrices, 9*9 - 9 = 72 calls are made in ~1 s). However, operating on all the data requires almost 25 million calls. I have also tried using deal() to make a cell array composed entirely of the next element in data, so I could use cellfun() in a single loop: # who(), load() and struct2cell() calls place k data matrices in a 1D cell array called data. nextData = cell(k,1); for i=1:k [nextData{:}] = deal(data{i}); H{:,i} = cellfun(@compare,data,nextData,'UniformOutput',false); end Unfortunately, this is not really any faster, because all the time is in compare(). Both of these code examples seem ill-suited for parallelization. I'm having trouble figuring out how to make my variables sliced. compare() is totally vectorized; it uses matrix multiplication and conv2() exclusively (I am under the impression that all of these operations, including the cellfun(), should be multithreaded in MATLAB?). Does anyone see a (explicitly) parallelized solution or better vectorization of the problem?

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  • C#, How to download file into string with progress callback?

    - by Kaminari
    I would like to use the WebClient (or there is another better option?) but there is a problem. I understand that opening up the stream takes some time and this can not be avoided. However, reading it takes a strangely much more amount of time compared to read it entirely immediately. Of course it's not working good because i'm not so familiar with streams. Is there a best way to do this? I mean two ways, to string and to file. Progress is my own delegate and it's working good. FIRST UPDATE: Ok, now i got something like this and it seems to work but still slow: System.Net.WebClient client = new System.Net.WebClient(); System.IO.Stream streamRemote = client.OpenRead(new Uri(URL)); if (savePath == null) { StreamReader reader = new StreamReader(streamRemote); int iByteSize = 0; byte[] byteBuffer = new byte[iSize]; char[] charBuffer = new char[iSize]; StringBuilder sb = new StringBuilder(); while ((iByteSize = reader.Read(charBuffer, 0, iSize)) > 0) { sb.Append(charBuffer, 0, iByteSize); iRunningByteTotal += iByteSize; float dIndex = (float)(iRunningByteTotal); float dTotal = (float)byteBuffer.Length; float dProgressPercentage = (dIndex / dTotal); float iProgressPercentage = (dProgressPercentage * 100); if (Progress != null) Progress(iProgressPercentage); } result = sb.ToString(); } Im wondering about DownloadStringAsync method?

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  • Replace occurance of character with all letters in the alphabet

    - by McAvoy
    I have created a scrabble game with a computer opponent. If a blank tile is found in the computer's rack during the word generation if needs to be swapped out for every letter in the alphabet. I have my current solution to solve this problem below, but was wondering if there is a better more efficient way to accomplish this task. if (str.Contains("*")) { char c = 'A'; String made = ""; while(c < 'Z') { made = str.ReplaceFirst("*", c.ToString()); if (!made.Contains("*")) { wordsMade.Add(made); if (theGame.theTrie.Search(made) == Trie.SearchResults.Found) { validWords.Add(made); } } else { char ch = 'A'; String made2 = ""; while (ch < 'Z') { made2 = made.ReplaceFirst("*", c.ToString()); wordsMade.Add(made2); if (theGame.theTrie.Search(made2) == Trie.SearchResults.Found) { validWords.Add(made2); } ch++; } } c++; }

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  • Using the read function to read in a file.

    - by robUK
    Hello, gcc 4.4.1 I am using the read function to read in a wave file. However, when it gets to the read function. Execution seems to stop and freezes. I am wondering if I am doing anything wrong with this. The file size test-short.wave is: 514K. What I am aiming for is to read the file into the memory buffer chunks at a time. Currently I just testing this. Many thanks for any suggestions, #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <fcntl.h> #include <string.h> #include <unistd.h> int main(void) { char buff = malloc(10240); int32_t fd = 0; int32_t bytes_read = 0; char *filename = "test-short.wav"; /* open wave file */ if((fd = (open(filename, O_RDWR)) == -1)) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } printf("Opened file [ %s ]\n", filename); printf("sizeof(buff) [ %d ]\n", sizeof(buff)); printf("strlen(buff) [ %d ]\n", strlen(buff)); bytes_read = read(fd, buff, sizeof(buff)); printf("Bytes read [ %d ]\n", bytes_read); return 0; }

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