C program to calculate area of circle?

Answer 1

/*to find the area of a circle*/

#include<stdio.h> #include<conio.h> main()

{

int r;

float a;

print f ("Enter r value \n");

scan f ("%d", &r);

a=3.14*r*r;

print f("area=%f",a);

}

Answer 2

#include<assert.h>

typedef struct rect_t {

int width;

int height;

} rect;

int area (rect* r) {

if (r==NULL) return 0;

return r->width * r->height;

}

int main (void) {

rect r;

int a;

r.width = 10;

r.height = 5;

a = area (&r);

assert (a==50);

return 0;

}

Answer 3

double areaofcircle (double radius) return 2. * 3.141592653589793 * radius;

Answer 4

double a,b,c,s,area;

double *parea = &area;

s=(a+b+c)/2;

*parea = sqrt (s*(s-a)*(s-b)*(s-c))