header-files

If I write a library, and have header files for development included, and have a src/Makefile.am like this: AM_CFLAGS = -std=c99 -Wall -Werror -Os lib_LTLIBRARIES = libmylibrary.la libmylibrary_la_SOURCES = a.c b.c include_HEADERS = a.h b.h Everything works nicely. However, a.h and b.h are installed directly under /usr/include (or /usr/local/include ). What should I do to get them installed, in a subdirectory specific to my library, e.g. /usr/include/mylibrary ? ptomato As well as pkginclude_HEADERS , which you mention, you can also install header files into an arbitrary subdirectory of /usr

COMPILER: g++ 4.7.2 Ok. So I am confused about default parameters in .h and .cpp files. It is mentioned in many places( including this site) that default parameters can be added only in .h files and not in .cpp files. However, this code proves it wrong: test1.h #pragma once #include <iostream> using namespace std; class Class{ public: Class(int, int, int=1); }; test1.cpp #include "test1.h" Class::Class(int a, int b=2, int c) { cout<<a<<" "<<b<<" "<<c<<endl; } int main() { Class a(1); return 0; } Now, according to what I have tested, default parameters can be added to .cpp files. However, the

There are some cases when we include .cpp file instead of standard header file (.h), for example: #include "example.cpp" instead of #include "example.h" It seems to work but is this safe or should I avoid it? What about the compilation time? It's lazy coding. Use header files. Yes they can increase compile time but they mean that you can easily re-implement chunks of your code, or better yet, another developer could at anytime. The header file serves as a template for what your C/C++ code is going to do. It's a bad idea to discard or ignore it. I agree with Kerrek SB. I did this once. I was

In our workflow, we can have a module A that is composed of several header files, module A not producing any binary (side note: it will obviously be used by other modules, that include some of the headers from module A to produce binaries). A good example would be a header-only library, for which CMake 3 introduces a good support thanks to the notion of INTERFACE library (see this SO answer , and CMake's documentation of the feature ). We can make an interface library target out of module A : add_library(module_A INTERFACE) That gives us all the nice features of CMakes targets (it is possible

I am studying the C language, and I saw a new extension that I had not seen before. What do files with the extension like library.h.in mean? Is it as the simple header with extension ".h"? What's the difference? These files are usually the input for autoconf which will generate final .h files. Here's an example from PCRE: #define PCRE_MAJOR @PCRE_MAJOR@ #define PCRE_MINOR @PCRE_MINOR@ #define PCRE_PRERELEASE @PCRE_PRERELEASE@ #define PCRE_DATE @PCRE_DATE@ Autoconf will replace all variables ( @…@ ) with the respective values and the result will be a .h file. Daniel Fischer Typically, a .h.in

In my C++ project when do I have to use inclusion ( #include "myclass.h" ) of header files? And when do I have to use forward declaration of the class ( class CMyClass; )? As a rule try the forward declaration first. This will reduce compile times etc. If that doesn't compile go for the #include . You have to go for the #include if you need to do any of the following: Access a member or function of the class. Use pointer arithmetic. Use sizeof. Any RTTI information. new / delete , copy etc. Use it by value. Inherit from it. Have it as a member. Instance in a function. (6,7,8,9 from @Mooing