Definition and Declaration

A function definition contains function name, parameters, its code and return type and A function declaration contains only name and return type.
User can define a function only once but it can be declared several times.

declaration of function

Syntax :
< return_type> < function_name>(arguments... );


/* Declaration of area() */

int area(int x, int y);
int main()
{
int x=10, y=25;   printf(''%d\n'',area(x,y)));
  return 0;
}


Definition of function

syntax
< return_type> < function_name>(arguments)
{
Body of function;
}

/* Definition of area() */

int area(int x, int y)
{
  int z;
  z = x*y;
  retrun z; }