WHAT IS HEADER FILE IN C LANGUAGE?

Header file is a file that contains function declaration and macro definition for C in-built library functions.

• All C standard library functions are declared in many header files which are saved as file_name.h.
• We are including these header files in our C program using “#include <file_name.h>” command to make use of the functions those are declared in the header files.
• When we include header files in our C program using “#include <filename.h>” command, all C code of the header files are included in C program. Then, this C program is compiled by compiler and executed.