Solution  :- 

#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
int radius;
float pi = 3.14,cir,dia,area;
printf(“Enter the Radius of a Circle :- “);
scanf(“%d”,&radius);
dia = 2*radius;
cir = 2*pi*radius;
area = pi * radius * radius;
printf(“\nThe Diameter of a Circle is :- %.2f”,dia);
printf(“\nThe Circumference of a Circle is :- %.2f”,cir);
printf(“\nThe Area of a Circle is :- %.2f”,area);
getch();
}