The return statement causes a return from a function, with or
   without a  return value.
   Syntax:

       return ;
       return expression ;

  The return value is undefined if not specified in a return
  statement.  If an expression is specified in the return statement,
  it is evaluated and the value is returned to the calling function;
  the value is converted, if necessary, to the type with which the
  called function was declared.  If a function does not have a return
  statement, the effect (on reaching the end of the function) is the
  same as with a return statement that does not specify an
  expression.  Functions declared as void may not contain return
  statements specifying an expression.