Function Call and Return in C - Digital College Library

A Function can be accessed i.e. called by specifying its name, followed by a list of arguments enclosed in parentheses and separated by commas.
If the function call does not require any arguments, an empty pair of parentheses must follow the name of the function.
The arguments within the function call are called actual parameters or actual arguments.
The actual arguments may be constants, variables or more complex expressions.
Each actual argument must be of the same type as its corresponding formal arguments.
Remember that it is the value of each actual arguments that is transferred into the function and assigned to the corresponding formal arguments.
The general form of function call is given below:

fun (a,b);

Where fun -> is the name of the function.
a, b -> are the actual arguments within the parentheses.
There will be no return value in this function call and it ends with;
If the function returns a value, then the function call is often written as an assignment statement e.g.

a = area (rad);
     or 
s = sum (n1, n2);

These functions will return a value and assigned to a and s respectively.
On the other hand if the function does not return anything, the function call will be e.g.

message ();

return (exp);

which can be a constant, variable or an expression, Parentheses around exp are optional.

The return statement need not always be at the end of the called function.
Also there is no restriction on the number of return statements that are present in the function.
But there is one limitations of return i.e. it can return only one value.

big (int a, int b)
{
    if (a > b)
       return(a);
  else
       return(b);
}

In the function, if the value of a is greater than b then a will be returned otherwise b will be returned to calling function.

Function Call and Return Statement in C Language with Free Notes