Difference between library and headers

[ripper079]

I cannot really grasp the diffence bettween a library and a header. I´ve checked the faq and found a "half" answer. It says "A header file is just a pointer to the .lib". Why do you then include both headers and libraries in the same source code???
Thx in advance

[zen]

A header file will contain all the decalarations for the functions in the library. You need the header file so the compiler can check that you are calling the functions in the library correctly (although the linker will produce an error if you try to call an undefined function), and you can use a header file if you don't have any other documentation about what functions the library contains.