计算圆的面积，int输入和计算

#include <stdio.h> 

int radius, area; 

int main()
{ 
    printf( "Enter radius (i.e. 10): " ); 
    scanf( "%d", &radius ); 
    area = (int) (3.14159 * radius * radius); 
    printf( "\n\nArea = %d\n", area ); 
    return 0; 
}