Wap “C” to find area of circle using Function

#include<stdio.h>
#include<conio.h>
void main()
{
   float aoc;
   aoc=3.14*(r*r);
   printf("area of circle is:%f",aoc);
}
void main() 
{
   float r;
  printf("Enter the radius:");
  scanf("%f",&r);
area of circle(r);
}

output:

Enter the radius: 7
area of circle is : 153.86