What is function?

                         Function

The group of instructions and statement
which perform any task togather.
Every c program has at least one function, which is main(),  all the most trivial programs can define additional function.

Defining aFunction

The general form of a function definition in C programming language is as follows:

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:

 

o   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.

 

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

 

 

o   Parameters: 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.

 

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

 

 

Example

Given below is the source code for a function called max(). This function takes two parameters num1 and num2 and returns the maximum value between the two:

 

/* function returning the max between two numbers */

int max(int num1, int num2)

{

/* local variable declaration */

int result;

if (num1 > num2)

result = num1;

else

result = num2;

return result;

}