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;
}
