Difference between header file and library file?

Answer 1

A header file is normally used for declarations to provide an interface that can be included into a source file that wants to use the functions/variables that have been declared. If the header file contains function prototypes, it will usually have a corresponding source file that defines the functions.

/* example.h */ #define bTRUE 1 #define bFALSE 0 typedef int BOOL BOOL bEvenNumber(unsigned int uiNumber); /* example.c */ #include "example.h" BOOL bEvenNumber( unsigned int uiNumber) { return (uiNumber & 1) ? bFALSE : bTRUE; }

Answer 2

A header file contains declaration of something (constants, classes, ...), usually ends with a .h or hpp extension.

A DLL (dynamically linked library) is a binary file (with .dll, .ocx, .a, ... extentions), containing functions, resources, ... and can be linked to your program at run-time. In order to use a DLL you need to include the corresponding header file, which declares things in the DLL, so that your program gets compiled. The DLL file is automatically loaded (by system) at run-time when your executable program invokes functions and asks for resources.

A library file (also called static library, with .lib extension usually) is a binary file which also contains functions and variables like DLL, but resolved at compile-time, meaning they need to be provided at link-time.

Dynamic and static libraries are often provided together with header file (but no source file, which contains the implementation) when the provider lets you use his/her functions/services but doesn't give you access to the implementation.

Answer 3

Header file contains only the declaration of the function being used. While, the library file has the files of the declared function in the header file.