C Programming Language

Function in C

A function is a group of statements that together perform a task. Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions.

A function declaration tells the compiler about a function's name, return type, and parameters. A function definition provides the actual body of the function.

Defining Function :
return_type function_name( parameter_list )
   body of the function


A function definition in C programming consists of a function header and a function body. Here are all the parts of a function :

Return Type : A function may return a value. The return_type is the data type of the value the function returns. Some functions perform the desired operations without returning a value. In this case, the return_type is the keyword void.

Function Name : This is the actual name of the function. The function name and the parameter list together constitute the function signature.

Parameter : A parameter is like a placeholder. When a function is invoked, you pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a function. Parameters are optional; that is, a function may contain no parameters.

Function Body :The function body contains a collection of statements that define what the function does.

Structure of Function :
Example of Function in c


Declaration of Function :

A function declaration tells the compiler about a function name and how to call the function. The actual body of the function can be defined separately.
return_type function_name( parameter list );
For the above defined function max(),the function declaration is as follows:
int max(int num1, int num2);
Parameter names are not important in function declaration, only their type is required, so the following is also a valid declaration
int max(int, int);


Example :

Output :

Max value of a is : 10