header-files

问题 I use MPI in a C program in Visual Studio Code on Windows. I compile and run it in WSL just fine, but VSCode warns me that it can't find mpi.h : I have installed libopenmpi-dev in WSL and added the header directories to VSCode's settings ( .vscode/c_cpp_properties.json ): { "configurations": [ { "name": "WSL", "includePath": [ "${workspaceFolder}/**", "/usr/lib/gcc/x86_64-linux-gnu/7/include", "/usr/local/include", "/usr/lib/gcc/x86_64-linux-gnu/7/include-fixed", "/usr/include/x86_64-linux

问题 I have looked at these links : This one and This and a couple of other similar ones. None of the answers given here are working methods are working. I have a two source files a1.c , a2.c and two header files a1.h and a2.h . I want to include the header files in both these files (and a2.c in a1.c as there is a function I need to use from a2.c) I have included #include "a1.h" #include "a2.h" in the source files of a1.c I'm using GCC on Ubuntu. and using the command gcc a1.h -o a1.out -lm and

问题 I was looking here how to do static libraries using GCC, and the explanation is pretty clear (despise the fact I had to rewrite the factorial function): I have a function (fact.c), the header of the function (fact.h), and the main function (main.c), all of them in my home directory. fact.h int fact (int); fact.c int fact (int f) { if ( f == 0 ) return 1; else return (f * fact ( f - 1 )); } main.c #include <stdio.h> #include "fact.h" int main(int argc, char *argv[]) { printf("%d\n", fact(3));

问题 When you include a header file (.h, .hpp, .hh, .hxx extensions) from the C Standard Library or the C++ STL (or even include a Microsoft's big one like windows.h ), and use only a certain limited number of functions from it, does the whole file become binary and be copied to the executable file, or just the specific, relevant functions that are being used become binary? If the whole file is being copied (and that's what I think actually happens, since windows.h has macro-defines to reduce

问题 Decided to check out some code other than my own, Quake I was the choice. The first file I click on is filled with nothing but raw data and the only comments are the GPL. I am guessing it is an array containing normal vectors? Regardless of what its purpose was, what confuses me is what it is doing in a header file anorms.h. I am wondering what could be the purpose of doing this? The other source, actual code, feels fairly complicated to me. As a novice programmer I probably just need to

问题 I am trying to get C header files for COM interfaces using OLE/COM object viewer. I have tries to save type library as header file in object viewer, however, after a cmd window flashes, nothing happens. I have tried to save it as IDL file and convert to header file myself using this command; midl /out C:\temp /header EXCEL.h EXCEL.IDL However, I am getting this error: Microsoft (R) 32b/64b MIDL Compiler Version 7.00.0555 Copyright (c) Microsoft Corporation. All rights reserved. 64 bit

问题 I was wondering what were the default values of variables before I initialized them... For example, if I do : //myClass.h BOOL myBOOL; // default value ? NSArray *myArray; // default value ? NSUInteger myInteger; // default value ? Some more examples here : //myClass.m // myArray is not initialized, only declared in .h file if ([myArray count] == 0) { // TRUE or FALSE ? // do whatever } More generally, what is returned when I do : [myObjectOnlyDeclaredAndNotInitialized myCustomFunction];

问题 Can somebody please explain this? #include <iostream> #include <limits.h> or #include <iostream> #include <limits> 回答1: <limits> is a C++ Standard Library header providing similar insights to the C header <limits.h> (which is also available in C++ as <climits>), but it is written in a way that's more useful and safe in C++ programs: say you have a template <typename Numeric> ... , and the code inside wants to know the minimum and maximum value of the Numeric type parameter that the user

问题 During compilation I get a "multiple definition" error, which refers to a template specialisation in a header file. Do I need to put the specialisations into the source file? 回答1: If it is functions you have specialized, you can either put them in the .cpp file, or make them inline in the header. Like James points out, if you don't make the functions inline, you still have to declare the specializations in the header. Otherwise the compiler doesn't know it has to look for them elsewhere. You

问题 I want to access source file of string.h . I mean the file which have definitions of all functions available in string.h . For example strcpy() is a function in string.h ; where can I get its definition, as string.h only gives prototypes of functions? 回答1: You didn't specify a developer tool - this answer is for Visual Studio 2008 on Windows. CRT sources can be found under: C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\crt\src\ if it's installed at the default location. For other