How to view source code of header file in C++?

similar to iostream.h 开发者_运维问答,conio.h , ...

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The standard library is generally all templates. You can just open up the desired header and see how it's implemented^†. Note it's not <iostream.h>, it's <iostream>; the C++ standard library does not have .h extensions. C libraries like <string.h> can be included as <cstring> (though that generally just includes string.h)

That said, the run-time library (stuff like the C library, not-template-stuff) is compiled. You can search around your compiler install directory to find the source-code to the run-time library.

Why? If just to look, there you go. But it's a terrible way to try to learn, as the code may have non-standard extensions specific to the compiler, and most implementations are just generally ugly to read.

If you have a specific question about the inner-workings of a function, feel free to start a new question and ask how it works.

_{† I should mention that you may, on the off chance, have a compiler that supports export. This would mean it's entirely possible they have templated code also compiled; this is highly unlikely though. Just should be mentioned for completeness.}

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From a comment you added, it looks like you're looking for the source to the implementations of functions that aren't templates (or aren't in the header file for whatever reason). The more traditional runtime library support is typically separately compiled and in a library file that gets linked in to your program.

The majority of compilers provide the source code for the library (though it's not guaranteed to be available), but the source files might be installed anywhere on your system.

For the Microsoft compilers I have installed, I can find the source for the runtime in a directory under the Visual Studio installed location named something like:

vc\crt\src        // VS2008
vc7\crt\src       // VS2003
vc98\crt\src      // VC6

If you're using some other compiler, poke around the installation directory (and make sure that you had asked that runtime sources to be installed when you installed your compiler tools).

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As mentioned, it is implementation specific but there is an easy way to view contents of header files.

• Compile your code with just preprocessing enabled for gcc and g++ it is -E option.
  This replaces the contents of header files by their actual content and you can see them.

• On linux, you can find some of them in /usr/include

• These files merely contain declarations and macro definitions.The actual implementation source files can be obtained from the library provider e.g the source code of standard C++ Library(libstdc++) is obtainable here.

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According to the C++ language specification, implementors do not have to put standard headers into physical files. Implementors are allowed to have the headers hard coded in the translator's executable.

Thus, you may not be able to view the contents of standard header files.