作業(yè)二：圓的面積

```

#include

#define?PI?3.14

double?calculateArea?(int?radius);

int?main?()

{

int?cRadius?=0;

double?Area?=0.0;

printf("請輸入圓的半徑:\n");

scanf("%d",&cRadius);

Area=calculateArea(cRadius);

printf("圓的面積是:%f\n",Area);

return?0;

}

double?calculateArea?(int?radius)

{

double?result?=?PI*radius*radius;

return?result;

}

```