c++

How to get the nth root of big numbers in C++?

Is there a C++ library that can take nth roots of big numbers (numbers than can't fit in an unsigned long long)? ...

How to initialize an unsigned long long type?

I'm trying to initialize an unsigned long long int type. But the compiler is throwing an error "error: integer constant is too large for "long" type ". The initialization is shown below : unsigned long long temp = 1298307964911120440; Can anybody please let me know what the problem is and suggest a solution for the same. ...

Why are most really fast servers written in C instead of C++?

I'm trying to decide which to learn and I've read all the "Which is better" questions/arguments, so I thought I'd get your take on something more specific. Is there a platform dependency issue that C++ developers run into with such applications? Or, is it because there are more C developers out there than C++? I also noticed that many m...

precompiled header .pch files are machine sensitive?

Hi, experts, I tried to reuse the .pch to speed the build using the following way: use /Yc on stdafx.cpp to create the .pch files to a folder exclude stdafx.cpp in the project, and modify the link option It success in my machine, but failed in another, got the error message: error C2011: '*' : 'struct' type redefinition So first I ...

Function with missing return value, behavior at runtime

As expected, the compiler (VisualStudio 2008) will give a warning warning C4715: 'doSomethingWith' : not all control paths return a value when compiling the following code: int doSomethingWith(int value) { int returnValue = 3; bool condition = false; if(condition) // returnValue += value; // DOH return...

length of va_list when using variable list arguments?

Is there any way to compute length of va_list? All examples I seen the number of variable parameters is given explicitly. ...

Is there any reasonable use of a function returning an anonymous struct?

Here is an (artificial) example of using a function that returns an anonymous struct and does "something" useful: #include <iostream> template<typename T> T* func( T* t, float a, float b ) { if(!t) { t = new T; t->a = a; t->b = b; } else { t->a += a; t->b += b; } retu...

Can I define a variable in Visual Studio debugger?

Hi, guys. I am wondering if I could define a variable during debugging in visual studio. For instance, I want to know how many times the breakpoint was hit when some flag was true. This rquirement seems need more advanced programmable skill to visual studio debugger. Visual studio conditional breakpoint can only satisfy partial requirem...

Timestamp issue with localtime and mktime

Please see the code below: #include <iostream> #include <stdlib.h> #include <time.h> using namespace std; int main(void) { time_t current_time = 1270715952; cout << "Subscriber current timestamp:" << current_time << endl; tm* currentTm = localtime(&current_time); char tmp_str[256]; //2010-04-08T11:39:12 ...

C++: Failure to get data through pipe when using wide strings in both programs

Hi, I’m trying to use the following code in C++ on Mac OS X Snow Leopard to get the output of an external program through a pipe. FILE * al = popen("program program.cfg", "r"); string data; char buffer[100]; while (fgets(buffer, 100, al) != NULL) data.append(buffer); cout << "«" << data << "»" << endl; pclose(al); However, no data g...

Safe division function

I would like to define some kind of safe division (and modulo) function, one that would return some predefined value when attempting to divide by zero. I don't want to throw exceptions, just to return some "reasonable" value (1? 0?) and continue the program flow. Obviously there is no correct return value, but I wonder if there is some s...

C++ Array of Variable sized Arrays

I am very new to C++ and I realise the following is not necessarily as easy as I'd like it to be, but I'd really appreciate a more expert opinion. I am essentially trying to achieve a dynamic iteration over a variable sized array of variable sized arrays similar to the following. String *2d_array[][] = {{"A1","A2"},{"B1","B2","B3"},{"C...

About enumerations in Delphi and c++ in 64-bit environments

I recently had to work around the different default sizes used for enumerations in Delphi and c++ since i have to use a c++ dll from a delphi application. One function call returns an array of structs (or records in delphi), the first element of which is an enum. To make this work, I use packed records (or aligned(1)-structs). However,...

toupper/tolower + locale (german)

Hi, how to convert a string (wstring) from lowercase to uppercase characters and vice versa? I searched the net and found there is a STL-function std::transform. But until now I hav'nt figured out how to give the right locale-object for example "Germany_german" to the function. Who can help please? my code looks like: wstring strin =...

C++ Expression Templates

Hi, I currently use C for numerical computations. I've heard that using C++ Expression Templates is better for scientific computing. What are C++ Expression Templates in simple terms? Are there books around that discuss numerical methods/computations using C++ Expression Templates? In what way, C++ Expression Templates are better than...

Creating a MiniDump of a running process

Im trying to make a tool for my end users that can create a MiniDump of my application if it hangs (i.e. external to the app). Im using the same code as the internal MiniDumper but with the handle and processid of the app but i keep getting error code 0xD0000024 when calling MiniDumpWriteDump. Any ideas? void produceDump( const char* ex...

Polymorphic Queue

Hello Everyone, I'm trying to implement a Polymorphic Queue. Here is my trial: QQueue <Request *> requests; while(...) { QString line = QString::fromUtf8(client->readLine()).trimmed(); if(...)){ Request *request=new Request(); request->tcpMessage=line.toUtf8(); ...

gethostbyname replacement for IPv6 addresses

Hi, I have a program that uses gethostbyname (in Windows) in order to convert IP address to hostname. But, it works only for IPv4... What is the correct replacement for IPv6? Thanks. ...

How do you debug c/c++ source code in linux using emacs?

Hello all, I am using emacs and autotools, to write and compile c/c++ sources on linux. I am using gdb via GUD in emacs. I have defined for convenience: F7:compile, F10:gud-next, F11:gud-step, F5:gud-cont, F9:gud-tbreak, F8:gud-until, F4:gud-print. I am mainly interested in debugging c/c++ source code on linux from emacs and I would lik...

About variadic templates

Hi, I'm currently experiencing with the new c++0x variadic templates, and it's quite fun, Although I have a question about the process of member instantiation. in this example, I'm trying to emulate the strongly typed enum with the possibility of choose a random valid strong enum (this is used for unit testing). #include<vector> #in...