Functions

A function is a block of statements, which is used to perform a specific task.

A C program has at least one function named main().

Types of functions :

There are two types of function in C

• Library function
• User defined function

Library Function :

Library functions are the built-in function in C such as puts(), gets(), printf(), scanf() etc. These are the functions which already have a definition in header files.

User defined function :

C allows programmer to define their own function according to their requirement.

Syntax of function :

return_type function_name (argument list)
{
    Block of code
}

return_type : return types are the type of data that is returned by the function. If nothing is returned then the return type is void.

argument list : argument list contains variables names along with their data types. These arguments are inputs for the function.

Syntax :

#include <stdio.h>

void function_name()
{
    //code
}

int main()
{
    //Calling function
    function_name();
}

Example :

    #include<stdio.h>

    /* function return type is void and doesn't have parameters*/
    void demo()
    {
    printf("Hello World");
    }

    int main()
    {
    /*calling function*/
    demo();
    return 0;
    }

Output :

Hello World

Explanation :

demo() is a user defined function, and in main(), demo() function is called so that it can perform its task.