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Header Files Overview

Header files in C​

  • Header files contain declarations of functions, variables, and other identifiers that are used in a program.

  • Header files typically have a .h extension and are included in a C program using the #include directive.

Types of header files​

There are two main types of header files:

Standard Library Header Files​

  • The standard library inclusion is used to include standard header files that define functions, constants, and macros used in C programming.

  • These header files are usually provided by the compiler or the operating system, and are included using angle brackets (<>) as follows:

#include <stdio.h>

User-defined Header Files​

  • USer-defined Header Files or Custom header files are created by the programmer to define functions, constants, and macros that are specific to a particular program or module.

  • These header files are included using double quotes ("") as follows:

#include "myheader.h"
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  • The angle brackets <> are used to include standard library header files, while double quotes "" are used to include user-defined header files.

  • User-defined header files are typically used to organize the code in a C program and to separate the interface (the declarations in the header file) from the implementation (the code in the C source file). This makes it easier to modify and maintain the code in a large program.

Purpose and Benefits of Header Files​

Declare functions, Variables​

Header files allow you to declare functions, variables, and other constructs that are used in your C program but defined elsewhere.

Share Code​

Header files provide a convenient way to share code across multiple C source files.

Organize Code​

Header files help to organize your code by separating interface (declaration) from implementation (definition).

Code Readability​

Header files can improve code readability by allowing you to hide implementation details and expose only a simplified interface to the user.

Code Maintainability​

Header files can improve code maintainability by making it easier to modify or update code in a modular way.

Define Macros​

Header files can be used to define macros and constants that are used throughout your C program.

Access to Library​

Header files provide access to the functions and types defined in the standard C library and other libraries that your program may use.