Area and Circumference of Circle

In this program, # is a preprocessor directive ,  whereas #include<filename.h> is used

to extract the functions already created in file .float r creates a float type variable

which stores radius given by user . area of circle = 3.14*radius & radius & 

circumference of circle = 2*3.14*radius which are stored in ar & cir respectively .  

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Program for Area and Circumference of Circle.

#include<stdio.h>
#include<conio.h>
void main()
{ float ar,cir,r;
clrscr();
printf("\n program to calculate area & circumference of circle");
printf("\n\n enter radius of circle : ");
scanf("%f",&r);
ar = 3.14*r*r;
cir = 2*3.14*r;
printf("\n area of circle = %f",ar);
printf("\n circumference of circle = %f",cir);
getch();
}