#include<stdio.h>
#include<conio.h>
int main()
{
float r,result=0;  \\ variable declaration
clrscr();
printf("\n Enter Redius of Circle"); \\enter value
scanf("%f",&r);
result=3.14*r*r;         \\ perform operation
printf("\n Redius of Circle =%f",result);
return 0;
getch(); \\ it hold the output screen ,get one character then exit.
}