Why we use Header Files

[Jaiwanti]

I am just started the 'c' programming. I am getting confused regarding the header files which we use at the begining of program.

Should we have to include header files in all programs? OR it is optional.
Can anyone know what are different header file?

[Praetor]

A Header file is a file which contains C declarations as well as definitions of macro to be shared between many source files. we request the use of a header files in our program code by including it along with the C pre-processor directive i.e`#include'.

Below are the use of header files

1. Header files of system declares the interfaces to parts of the operating system. We include them in our program code to pass the definitions & declarations we need to invoke calls of system and libraries of system.

2. our own header files includes declarations for interfaces between the program source files.
Every time we have a group of related declarations & definitions or more of which are needed in many different program source files,So it's a good to create a header files for them.

[Katty]

According to my knowledge, a header files are used to declares variables, constants and functions which may be common to many applications.

When a system comprises of multiple applications that all access the same data which becomes very essential that each and every application uses similar definitions .So it is also safer for all of those applications to use the similar methods for reading that data.

I hope this information will give you the idea about header files..

[kelfro]

Hi friend,

The main use of header file is it is used to share information within various files.

1.Suppose, if you have several functions say three functions named as A1, A2, A3, f4 which are placed in file 'abc.c' and if all the functions want to get accessed by each other then all functions must be placed within same file 'abc.c'.

2. see the another example, if there is a function 'A4' placed in another file say 'xyz.c' and if the function A1 placed in 'abc.c' wants to access the 'A4' function placed in 'xyz.c',then it is impossible.