C Header Files

In this tutorial you will learn about the C Header Files and its application with practical example.

In C Programming Language Header Files gives us a way to reuse the external declarations, functions, or macro definition and allows us to share between other source files. When you include a header file, the compiler adds the functions, data types, and other information in the header file to the list of reserved words and commands in the language. We can include a header file in our program using C Preprocessor Directive “#include”, Header files almost always have a .h extension. Including a header file produces the same result as you copy the source code in your program.

Table Of Contents−

In C Programming Language Headers files are used for the following purpose –

  • It enables you to include system or operating system-related macro definitions and functions so that you can invoke system calls and libraries.
  • You can create your own custom header files so that you can reuse and share them.
  • It makes the program more manageable.
  • It increases the portability of the program.

One of the most commonly used header files is for the standard input/output routines is called stdio. h.

We can include header files in the following two ways –

includes a header file from the current directory (the directory in which your C source code file appears), and

includes a file from a system directory.

Type Of Header Files

Standard Header Files

It is the set of header files used for performing various common and standard operations.

stdio. h – Defines core input and output functions

string.h – Defines string handling functions.

time.h – Defines date and time handling functions

math.h – Defines common mathematical functions.

User-Defined Header Files

In C Programming Language users can have their own custom header file that provides additional capabilities.

How to Create Your Own Header File in C Programming Language

Step #1

Type the below source code in a file

Put only function definition as you write in General C Program

Step #2

  • Save Above Code with [.h ] Extension.
  • Let the name of our header file be my head [ my head.h ]
  • Compile Code if required.

Step #3

Write Main Program

  • Include Our New Header File.
  • Instead of writing < my head.h> use this terminology “my head.h”
  • All the Functions are defined in the head.h header files are now ready for use.
  • Directly call function to add(); [ Provide proper parameter and take care of return type ]

While running your program both files (my head. h and sample. c) should be in the same directory.

In this tutorial we have learn about the C Header Files and its application with practical example. I hope you will like this tutorial.