(a) Header file

• A header file is a file with extension .h which contains C function declarations and macro definitions to be shared between several source files.
• 2 types - files that programmer writes

$\hspace{2.5cm}$- files that comes with compiler

For example:

$\underbrace{\#include}_{\text{preprocessor directive to call header file}}$ $\underbrace{\lt stdio.h\gt}_{\text{header …