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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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  • Base class Undefined WEIRD problem . Need help

    - by nXqd
    My CGameStateLogo which inherit from CGameState: CGameStateLogo.h #pragma once #include "GameState.h" class CGameMain; class CGameState; class CGameStateLogo: public CGameState { public: void MessageEnter (); void MessageUpdate( int iKey ); void MessagePaint( HDC* pDC ); public: CGameStateLogo(CGameMain* pGameMain); CGameStateLogo(void); ~CGameStateLogo(void); }; CGameState.h #pragma once #include "GameMain.h" #include "MyBitmap.h" class CGameMain; class CMyBitmap; class CGameState { public: CMyBitmap* pbmCurrent; CGameMain* pGM; int GameStateID; virtual void MessageEnter () = 0; virtual void MessageUpdate( int iKey ) = 0; virtual void MessagePaint( HDC* pDC ) = 0; void StateHandler ( int msg, HDC* pDC, int key ); public: CGameState(void); ~CGameState(void); }; Thanks for reading this :)

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  • Reversing strings in a vector using for_each and bind

    - by fmuecke
    Hi! I was wandering how it's possible to reverese strings that are contained in a vector using a single for_each command just in one "simple" line. Yea, I know it is easy with a custom functor, but I can't accept, that it can't be done using bind (at least I couldn't do it). #include <vector> #include <string> #include <algorithm> std::vector<std::string> v; v.push_back("abc"); v.push_back("12345"); std::for_each(v.begin(), v.end(), /*call std::reverse for each element*/); Edit: Thanks a lot for those funtastic solutions. However, the solution for me was not to use the tr1::bind that comes with the Visual Studio 2008 feature pack/SP1. I don't know why it does not work like expected but that's the way it is (even MS admits that it's buggy). Maybe some hotfixes will help. With boost::bind everything works like desired and is so easy (but sometimes relly messy:)). I really should have tried boost::bind in the first place...

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  • c++ STL vector is not acccepting the copy constructor

    - by prabhakaran
    I wrote a code ( c++,visual studio 2010) which is having a vector, even I though copy const is declared, but is still showing that copy const is not declared Here the code #include<iostream> #include<vector> using namespace std; class A { public: A(){cout << "Default A is acting" << endl ;} A(A &a){cout << "Copy Constructor of A is acting" << endl ;} }; int main() { A a; A b=a; vector<A> nothing; nothing.push_back(a); int n; cin >> n; } The error I got is Error 1 error C2558: class 'A' : no copy constructor available or copy constructor is declared 'explicit' c:\program files\microsoft visual studio 10.0\vc\include\xmemory 48 1 delete Anybody please help me

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  • Infile incomplete type error

    - by kd7vdb
    I am building a program that takes a input file in this format: title author title author etc and outputs to screen title (author) title (author) etc The Problem I am currently getting is a error "ifstream infile has incomplee type and cannot be defined" #include <iostream> #include <string> #include <ifstream> using namespace std; string bookTitle [14]; string bookAuthor [14]; int loadData (string pathname); void showall (int counter); int main () { int counter; string pathname; cout<<"Input the name of the file to be accessed: "; cin>>pathname; loadData (pathname); showall (counter); } int loadData (string pathname) // Loads data from infile into arrays { ifstream infile; int counter = 0; infile.open(pathname); //Opens file from user input in main if( infile.fail() ) { cout << "File failed to open"; return 0; } while (!infile.eof()) { infile >> bookTitle [14]; //takes input and puts into parallel arrays infile >> bookAuthor [14]; counter++; } infile.close; } void showall (int counter) // shows input in title(author) format { cout<<bookTitle<<"("<<bookAuthor<<")"; } Thanks ahead of time, kd7vdb

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  • how to solve a weired swig python c++ interfacing type error

    - by user2981648
    I want to use swig to switch a simple cpp function to python and use "scipy.integrate.quadrature" function to calculate the integration. But python 2.7 reports a type error. Do you guys know what is going on here? Thanks a lot. Furthermore, "scipy.integrate.quad" runs smoothly. So is there something special for "scipy.integrate.quadrature" function? The code is in the following: File "testfunctions.h": #ifndef TESTFUNCTIONS_H #define TESTFUNCTIONS_H double test_square(double x); #endif File "testfunctions.cpp": #include "testfunctions.h" double test_square(double x) { return x * x; } File "swig_test.i" : /* File : swig_test.i */ %module swig_test %{ #include "testfunctions.h" %} /* Let's just grab the original header file here */ %include "testfunctions.h" File "test.py": import scipy.integrate import _swig_test print scipy.integrate.quadrature(_swig_test.test_square, 0., 1.) error info: UMD has deleted: _swig_test Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 523, in runfile execfile(filename, namespace) File "D:\data\haitaliu\Desktop\Projects\swig_test\Release\test.py", line 4, in <module> print scipy.integrate.quadrature(_swig_test.test_square, 0., 1.) File "C:\Python27\lib\site-packages\scipy\integrate\quadrature.py", line 161, in quadrature newval = fixed_quad(vfunc, a, b, (), n)[0] File "C:\Python27\lib\site-packages\scipy\integrate\quadrature.py", line 61, in fixed_quad return (b-a)/2.0*sum(w*func(y,*args),0), None File "C:\Python27\lib\site-packages\scipy\integrate\quadrature.py", line 90, in vfunc return func(x, *args) TypeError: in method 'test_square', argument 1 of type 'double'

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  • Why does my program not react to any arguments?

    - by Electric Coffee
    I have a simple test program in C++ that prints out attributes of a circle #include <iostream> #include <stdlib.h> #include "hidden_functions.h" // contains the Circle class using namespace std; void print_circle_attributes(float r) { Circle* c = new Circle(r); cout << "radius: " << c->get_radius() << endl; cout << "diameter: " << c->get_diameter() << endl; cout << "area: " << c->get_area() << endl; cout << "circumference: " << c->get_circumference() << endl; cout << endl; delete c; } int main(int argc, const char* argv[]) { float input = atof(argv[0]); print_circle_attributes(input); return 0; } when I run my program with the parameter 2.4 it outputs: radius: 0.0 diameter: 0.0 area: 0.0 circumference: 0.0 I've previously tested the program without the parameter, but simply using static values, and it ran just fine; so I know there's nothing wrong with the class I made... So what did I do wrong here? Note: the header is called hidden_functions.h because it served to test out how it would work if I had functions not declared in the header

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  • In C, when do structure names have to be included in structure initializations and definitions?

    - by Tyler
    I'm reading The C Programming Language by K&R and in the section on structures I came across these code snippets: struct maxpt = { 320, 200 }; and /* addpoints: add two points */ struct addpoint(struct point p1, struct point p2) { p1.x += p2.x; p1.y += p2.y; return p1; } In the first case, it looks like it's assigning the values 320 and 200 to the members of the variable maxpt. But I noticed the name of the struct type is missing (shouldn't it be "struct struct_name maxpt = {320, 200}"? In the second case, the function return type is just "struct" and not "struct name_of_struct". I don't get why they don't include the struct names - how does it know what particular type of structure it's dealing with? My confusion is compounded by the fact that in previous snippets they do include the structure name, such as in the return type for the following function, where it's "struct point" and not just "struct". Why do they include the name in some cases and not in others? /* makepoint: make a point from x and y components */ struct point makepoint(int x, int y) { struct point temp; temp.x = x; temp.y = y; return temp; }

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  • Changing file permissions in kernel.

    - by Mehrdad
    I am writing kernel module(C in Linux) and I want to change the permission of the other files in it. any solution? since I am in kernel I can't use chmod syscall and ... thanks for your help This is my Makefile: > obj-m += ca.o > > all: > make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules > > clean: > make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean And this is my Code: > #include <linux/string.h> > #include <linux/mm.h> > /* Snip, tons of includes (all of them :))*/ > #include <linux/delay.h> .... int procfile_write(struct file *file, > const char *buffer, unsigned long > count, > void *data) { ... sys_chmod(path, per); ... } ... When Making it gives a warning: WARNING: "sys_chmod" [file] undefiened and when loading the module with "sudo insmod" it gives this error: Unknown sybol in module it seems that this error happens especialy in kernel modules. any idea? again thanks!

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  • __declspec(dllimport) causes compiler crash on MSVC 2010

    - by Zero
    In a *.cpp file, trying to use a third party lib: #define DLL_IMPORT #include <thirdParty.h> // Third party header has code like: // #ifdef DLL_IMPORT // #define DLL_DECL __declspec(dllimport) // fatal error C1001: An internal error has occurred in the compiler. Alternative: #define NO_DLL #include <thirdParty.h> // Third party header has code like: // #elif defined(NO_DLL) // #define DLL_DECL // Compiles fine, but linker errors as can't find DLL functions // I can reproduce results by remove macros and #define all together and manually editing the third party files to have __declspec(dllimport) or not Has anyone come across anything similar, or can hint at the cause? (which is created using CMake). Above is actual example of 2 line *.cpp that crashes so it's narrowed down to something in the #include. The following also work fine: Compile the examples provided by the third party (they provide a *.sln) that use dllimport/export so it doesn't appear to be the fault of the library Compile the third party lib as part of the production project (so dllexport works fine) I've trawled the project settings pages of the two projects to try and spot differences, but have come up blank. Of course, it's possible I'm missing something as those settings pages are not the easiest to navigate. I'll get access to VS2008 in a day or so, so can compare with that. The third party library is MySql++.

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  • (C++) Loading a file into a vector

    - by Alden
    This is probably a simple question, however I am new to C++ and I cannot figure this out. I am trying to load a binary file and load each byte to a vector. This works fine with a small file, but when I try to read larger than 410 bytes the program crashes and says: This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. I am using code::blocks on windows. This is the code: #include <iostream> #include <fstream> #include <vector> using namespace std; int main() { std::vector<char> vec; std::ifstream file; file.exceptions( std::ifstream::badbit | std::ifstream::failbit | std::ifstream::eofbit); file.open("file.bin"); file.seekg(0, std::ios::end); std::streampos length(file.tellg()); if (length) { file.seekg(0, std::ios::beg); vec.resize(static_cast<std::size_t>(length)); file.read(&vec.front(), static_cast<std::size_t>(length)); } int firstChar = static_cast<unsigned char>(vec[0]); cout << firstChar <<endl; return 0; } Thank you for your help!

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  • header location won't work in php

    - by Jayden Kelly
    I am making a login page for my website but the header location won't work. here is the code of login.php: <?php include ( './includes/header.php' ); if (isset($_POST['submit'])) { $username = $_POST['username']; $password = $_POST['password']; $check_username = mysql_query("SELECT username FROM users WHERE username='$username'"); $numrows = mysql_num_rows($check_username); if ($numrows != 1) { echo 'That User doesn\'t exist.'; } else { $check_password = mysql_query("SELECT password FROM users WHERE password='$password' && username='$username'"); while ($row = mysql_fetch_assoc($check_password)) { $password_db = $row['password']; if ($password_db == $password) { $_SESSION['username'] = $username; header("Location: members.php"); } } } } ?> <h2>Login to Your Account</h2> <form action='login.php' method='POST'> <input type='text' name='username' value='Username ...' onclick='value=""'/><p /> <input type='password' name='password' value='Password ...' onclick='value=""'/><p /> <input type='submit' name='submit' value='Login to my Account' /> </form> I would really appreciate it if someone could help me, thanks. P.S. If you need the php part of the header file it is here: <?php session_start(); include ( './includes/functions.php' ); include ( './includes/connect_to_mysql.php' ); ?>

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  • jQuery slide vertical images

    - by Mike
    Hello, I hope someone can help me with the following problem. I have a vertical scrollbar on my website which shows 5 images and will scroll 5 images further or back, depeding on where you clicked. The jQuery code looks like this. $(".productSlide .scrollable").scrollable(); $(".productSlide .scrollable").scrollable({ vertical: true, mousewheel: true }); I am new to jQuery and what I can achieve ist the following <div class="scrollBlock"> <?php for($i=0; $i<5; $i++) include 'example1.php'; ?> </div> <div class="scrollBlock"> <?php for($i=0; $i<5; $i++) include ' example1.php'; ?> </div> <div class="scrollBlock"> <?php for($i=0; $i<5; $i++) include ' example1.php'; ?> </div> In example1.php there is an image which will be showed 5 times. And everytime you click you’ll see the same div again with the same 5 pics. I can’t figure this one out without the "scrollBlock" div. How can I use more pictures in just one block – and it’s still scrolling 5 images? Thanks so much!

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  • Problem with passing array of pointers to struct among functions in C

    - by karatemonkey
    The Code that follows segfaults on the call to strncpy and I can't see what I am doing wrong. I need another set of eyes to look it this. Essentially I am trying to alloc memory for a struct that is pointed to by an element in a array of pointers to struct. #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_POLICY_NAME_SIZE 64 #define POLICY_FILES_TO_BE_PROCESSED "SPFPolicyFilesReceivedOffline\0" typedef struct TarPolicyPair { int AppearanceTime; char *IndividualFile; char *FullPolicyFile; } PolicyPair; enum { bwlist = 0, fzacts, atksig, rules, MaxNumberFileTypes }; void SPFCreateIndividualPolicyListing(PolicyPair *IndividualPolicyPairtoCreate ) { IndividualPolicyPairtoCreate = (PolicyPair *) malloc(sizeof(PolicyPair)); IndividualPolicyPairtoCreate->IndividualFile = (char *)malloc((MAX_POLICY_NAME_SIZE * sizeof(char))); IndividualPolicyPairtoCreate->FullPolicyFile = (char *)malloc((MAX_POLICY_NAME_SIZE * sizeof(char))); IndividualPolicyPairtoCreate->AppearanceTime = 0; memset(IndividualPolicyPairtoCreate->IndividualFile, '\0', (MAX_POLICY_NAME_SIZE * sizeof(char))); memset(IndividualPolicyPairtoCreate->FullPolicyFile, '\0', (MAX_POLICY_NAME_SIZE * sizeof(char))); } void SPFCreateFullPolicyListing(SPFPolicyPair **CurrentPolicyPair, char *PolicyName, char *PolicyRename) { int i; for(i = 0; i < MaxNumberFileTypes; i++) { CreateIndividualPolicyListing((CurrentPolicyPair[i])); // segfaults on this call strncpy((*CurrentPolicyPair)[i].IndividualFile, POLICY_FILES_TO_BE_PROCESSED, (SPF_POLICY_NAME_SIZE * sizeof(char))); } } int main() { SPFPolicyPair *CurrentPolicyPair[MaxNumberFileTypes] = {NULL, NULL, NULL, NULL}; int i; CreateFullPolicyListing(&CurrentPolicyPair, POLICY_FILES_TO_BE_PROCESSED, POLICY_FILES_TO_BE_PROCESSED); return 0; }

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  • How do I conditionally compile C code snippets to my Perl module?

    - by mobrule
    I have a module that will target several different operating systems and configurations. Sometimes, some C code can make this module's task a little easier, so I have some C functions that I would like to bind the code. I don't have to bind the C functions -- I can't guarantee that the end-user even has a C compiler, for instance, and it's generally not a problem to failover gracefully to a pure Perl way of accomplishing the same thing -- but it would be nice if I could call the C functions from the Perl script. Still with me? Here's another tricky part. Just about all of the C code is system specific -- a function written for Windows won't compile on Linux and vice-versa, and the function that does a similar thing on Solaris will look totally different. #include <some/Windows/headerfile.h> int foo_for_Windows_c(int a,double b) { do_windows_stuff(); return 42; } #include <path/to/linux/headerfile.h> int foo_for_linux_c(int a,double b) { do_linux_stuff(7); return 42; } Furthermore, even for native code that targets the same system, it's possible that only some of them can be compiled on any particular configuration. #include <some/headerfile/that/might/not/even/exist.h> int bar_for_solaris_c(int a,double b) { call_solaris_library_that_might_be_installed_here(11); return 19; } But ideally we could still use the C functions that would compile with that configuration. So my questions are: how can I compile C functions conditionally (compile only the code that is appropriate for the current value of $^O)? how can I compile C functions individually (some functions might not compile, but we still want to use the ones that can)? can I do this at build-time (while the end-user is installing the module) or at run-time (with Inline::C, for example)? Which way is better? how would I tell which functions were successfully compiled and are available for use from Perl? All thoughts appreciated!

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  • How to reduce the time of clang_complete search through boost

    - by kirill_igum
    I like using clang with vim. The one problem that I always have is that whenever I include boost, clang goes through boost library every time I put "." after a an object name. It takes 5-10 seconds. Since I don't make changes to boost headers, is there a way to cache the search through boost? If not, is there a way to remove boost from the auto-completion search? update (1) in response to answer by adaszko after :let g:clang_use_library = 1 I type a name of a variable. I press ^N. Vim starts to search through boost tree. it auto-completes the variable. i press "." and get the following errors: Error detected while processing function ClangComplete: line 35: Traceback (most recent call last): Press ENTER or type command to continue Error detected while processing function ClangComplete: line 35: File "<string>", line 1, in <module> Press ENTER or type command to continue Error detected while processing function ClangComplete: line 35: NameError: name 'vim' is not defined Press ENTER or type command to continue Error detected while processing function ClangComplete: line 40: E121: Undefined variable: l:res Press ENTER or type command to continue Error detected while processing function ClangComplete: line 40: E15: Invalid expression: l:res Press ENTER or type command to continue Error detected while processing function ClangComplete: line 58: E121: Undefined variable: l:res Press ENTER or type command to continue Error detected while processing function ClangComplete: line 58: E15: Invalid expression: l:res Press ENTER or type command to continue ... and there is no auto-compeltion update (2) not sure if clang_complete should take care of the issue with boost. vim without plugins does search through boost. superuser has an answer to comment out search through boost dirs with set include=^\\s*#\\s*include\ \\(<boost/\\)\\@!

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  • How can I close the output stream after a jsp has been included.

    - by stu
    I have a webpage that makes an ajax call to get some data. That data takes a long time to calculate, so what I did was the first ajax server call returns "loading..." and then the thread goes on to calculate the data and store it in a cache. meanwhile the client javascript checks back every few seconds with another ajax call to see if the cache has been loaded yet. Here's my problem, and it might not be a problem. After the initial ajax to the server call, I do a ...getServletContext().getRequestDispatcher(jsppath).include(request, response); then I use that thread to do the calculations. I don't mind tying up the webserver thread with this, but I want the browser to get the response and not wait for the server to close the socket. I can't tell if the server is closing the socket after the include, but I'm guessing it's not. So how can I forcibly close the stream after I've written out my response, before starting my long calculations? I tried o = response.getOutputStream(); o.close(); but I get an illegal state exception saying that the output stream has already been gotten (presumably by the jsp I'm including) So my qestions: 1) is the webserver closing the socket (I'm guessing not, because you could always include another jsp) 2) if it is as I assume not closing the socket, how do I do that?

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  • What's the meaning of 'char (*p)[5];'?

    - by jpmelos
    people. I'm trying to grasp the differences between these three declarations: char p[5]; char *p[5]; char (*p)[5]; I'm trying to find this out by doing some tests, because every guide of reading declarations and stuff like that has not helped me so far. I wrote this little program and it's not working (I've tried other kinds of use of the third declaration and I've ran out of options): #include <stdio.h> #include <string.h> #include <stdlib.h> int main(void) { char p1[5]; char *p2[5]; char (*p3)[5]; strcpy(p1, "dead"); p2[0] = (char *) malloc(5 * sizeof(char)); strcpy(p2[0], "beef"); p3[0] = (char *) malloc(5 * sizeof(char)); strcpy(p3[0], "char"); printf("p1 = %s\np2[0] = %s\np3[0] = %s\n", p1, p2[0], p3[0]); return 0; } The first and second works alright, and I've understood what they do. What is the meaning of the third declaration and the correct way to use it? Thank you!

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  • Operator Overloading << in c++

    - by thlgood
    I'm a fresh man in C++. I write this simple program to practice Overlaoding. This is my code: #include <iostream> #include <string> using namespace std; class sex_t { private: char __sex__; public: sex_t(char sex_v = 'M'):__sex__(sex_v) { if (sex_v != 'M' && sex_v != 'F') { cerr << "Sex type error!" << sex_v << endl; __sex__ = 'M'; } } const ostream& operator << (const ostream& stream) { if (__sex__ == 'M') cout << "Male"; else cout << "Female"; return stream; } }; int main(int argc, char *argv[]) { sex_t me('M'); cout << me << endl; return 0; } When I compiler it, It print a lots of error message: The error message was in a mess. It's too hard for me to found useful message sex.cpp: ???‘int main(int, char**)’?: sex.cpp:32:10: ??: ‘operator<<’?‘std::cout << me’????? sex.cpp:32:10: ??: ???: /usr/include/c++/4.6/ostream:110:7: ??: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostre

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  • Misaligned Pointer Performance

    - by Elite Mx
    Aren't misaligned pointers (in the BEST possible case) supposed to slow down performance and in the worst case crash your program (assuming the compiler was nice enough to compile your invalid c program). Well, the following code doesn't seem to have any performance differences between the aligned and misaligned versions. Why is that? /* brutality.c */ #ifdef BRUTALITY xs = (unsigned long *) ((unsigned char *) xs + 1); #endif ... /* main.c */ #include <stdio.h> #include <stdlib.h> #define size_t_max ((size_t)-1) #define max_count(var) (size_t_max / (sizeof var)) int main(int argc, char *argv[]) { unsigned long sum, *xs, *itr, *xs_end; size_t element_count = max_count(*xs) >> 4; xs = malloc(element_count * (sizeof *xs)); if(!xs) exit(1); xs_end = xs + element_count - 1; sum = 0; for(itr = xs; itr < xs_end; itr++) *itr = 0; #include "brutality.c" itr = xs; while(itr < xs_end) sum += *itr++; printf("%lu\n", sum); /* we could free the malloc-ed memory here */ /* but we are almost done */ exit(0); } Compiled and tested on two separate machines using gcc -pedantic -Wall -O0 -std=c99 main.c for i in {0..9}; do time ./a.out; done

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  • format, iomanip, c++

    - by Crystal
    I'm trying to learn to use namespaces declarations more definitive than not just say "using namespace std". I'm trying to format my data to 2 decimal places, and set the format to be fixed and not scientific. This is my main file: #include <iostream> #include <iomanip> #include "SavingsAccount.h" using std::cout; using std::setprecision; using std::ios_base; int main() { SavingsAccount *saver1 = new SavingsAccount(2000.00); SavingsAccount *saver2 = new SavingsAccount(3000.00); SavingsAccount::modifyInterestRate(.03); saver1->calculateMonthlyInterest(); saver2->calculateMonthlyInterest(); cout << ios_base::fixed << "saver1\n" << "monthlyInterestRate: " << saver1->getMonthlyInterest() << '\n' << "savingsBalance: " << saver1->getSavingsBalance() << '\n'; cout << "saver2\n" << "monthlyInterestRate: " << saver2->getMonthlyInterest() << '\n' << "savingsBalance: " << saver2->getSavingsBalance() << '\n'; } On Visual Studio 2008, when I run my program, I get an output of "8192" before the data I want. Is there a reason for that? Also, I don't think I am setting the fixed part or 2 decimal places correctly since I seem to get scientific notation once I added the setprecision(2). Thanks.

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  • hash tables and 2d vectors

    - by Sunil
    I want to push a 2d vector into a hash table row by row and later search for a row (vector) in the hash table and want to be able to find it. I want to do something like #include <iostream> #include <set> #include <vector> using namespace std; int main(){ std::set < vector<int> > myset; vector< vector<int> > v; int k = 0; for ( int i = 0; i < 5; i++ ) { v.push_back ( vector<int>() ); for ( int j = 0; j < 5; j++ ) v[i].push_back ( k++ ); } for ( int i = 0; i < 5; i++ ) { std::copy(v[i].begin(),v[i].end(),std::inserter(myset)); // This is not correct but what is the right way ? // and also here, I want to search for a particular vector if it exists in the table. for ex. the second row of vector v. } return 0; } I'm not sure how to insert and look up a vector in a set. So if nybody could guide me, it will be helpful. Thanks

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  • I am trying to access the individual bytes in a floating point number and I am getting unexpected results

    - by oweinh
    So I have this so far: #include <iostream> #include <string> #include <typeinfo> using namespace std; int main () { float f = 3.45; // just an example fp# char* ptr = (char*)&f; // a character pointer to the first byte of the fp#? cout << int(ptr[0]) << endl; // these lines are just to see if I get what I cout << int(ptr[1]) << endl; // am looking for... I want ints that I can cout << int(ptr[2]) << endl; // otherwise manipulate. cout << int(ptr[3]) << endl; } the result is: -51 -52 92 64 so obviously -51 and -52 are not in the byte range that I would expect for a char... I have taken information from similar questions to arrive at this code and from all discussions, a conversion from char to int is straightforward. So why negative values? I am trying to look at a four-byte number, therefore I would expect 4 integers, each in the range 0-255. I am using Codeblocks 13.12 with gcc 4.8.1 with option -std=C++11 on a Windows 8.1 device.

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  • What encoding does c32rtomb convert to?

    - by R. Martinho Fernandes
    The functions c32rtomb and mbrtoc32 from <cuchar>/<uchar.h> are described in the C Unicode TR (draft) as performing conversions between UTF-321 and "multibyte characters". (...) If s is not a null pointer, the c32rtomb function determines the number of bytes needed to represent the multibyte character that corresponds to the wide character given by c32 (including any shift sequences), and stores the multibyte character representation in the array whose first element is pointed to by s. (...) What is this "multibyte character representation"? I'm actually interested in the behaviour of the following program: #include <cassert> #include <cuchar> #include <string> int main() { std::u32string u32 = U"this is a wide string"; std::string narrow = "this is a wide string"; std::string converted(1000, '\0'); char* ptr = &converted[0]; std::mbstate_t state {}; for(auto u : u32) { ptr += std::c32rtomb(ptr, u, &state); } converted.resize(ptr - &converted[0]); assert(converted == narrow); } Is the assertion in it guaranteed to hold1? 1 Working under the assumption that __STDC_UTF_32__ is defined.

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  • rotate a star in opengl (2D)

    - by nova a
    I have a 2D star, and I don't know how to rotate it around its center, and I also don't know how to do it with a keyboard key. Also how can I make my object bigger or smaller by a certain percentage (because when I tried to do it by changing pixels, the star goes wrong). This is my code: #include <GL/glut.h> #include <GL/gl.h> #include <GL/freeglut.h> void init (void) { glClearColor(0.0,0.0,0.0,00); glMatrixMode(GL_PROJECTION); gluOrtho2D(0.0,200.0,0.0,200.0); } void LineSegment(void) { glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0,1.0,1.0); glBegin(GL_LINE_LOOP); glVertex2i(20,120); glVertex2i(180,120); glVertex2i(45,20); glVertex2i(100,190); glVertex2i(155,20); glEnd(); glFlush(); } int main(int argc,char** argv) { glutInit(&argc,argv); glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB); glutInitWindowPosition(50,100); glutCreateWindow("STAR"); init(); glutDisplayFunc(LineSegment); glutMainLoop(); return 0; }

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