What is a header file in C ? What will happen if we include a header file twice in a C program ?

webmaster — Fri, 07 Oct 2022 06:03:47 +0000

Header files store the definitions and rules for different built-in functions in the C program.
For example, printf(), scanf() functions are defined in stdio.h header file.
A header file is a file with extention .h which contains C function declarations and macro definitions to be shared between several source files.
There are two types of header file-files that a programmer writes and a file that comes with your compiler.
Every header file contains a set of predefined functions, which makes c programming simpler.
We should include the header file at the start of the program to be able to use the functions defined in the program.
When header files are added twice in a program, the compiler will process its contents twice.
This may cause an error when the compiler sees the same structure definition twice.

what are header files in c - Wikitechy