Write A C++ Program To Explain The Concept Of Function Prototyping.

#include <iostream.h> 
 #include<conio.h> 
 void main ( ) 
 { 
       float a,b,square(float); 
       clrscr(); 
       cout<<"\n Enter any Number : "; 
       cin>>a; 
       b = square(a); 
       cout<<"\n Square of "<<a<<" is "<<b; 
       getch(); 
 } 
       float square (float x) 
        { 
               float y; 
               y = x * x; 
               return (y); 
        }