int?main()
{
double?len,s1,s2,pi=3.1415926;
printf("請輸入正方形長:");
scanf("%lf",&len);
printf("正方形面積:%lf\n",s1=(len*len));
printf("內切圓面積:%lf\n",s2=(pi*0.25*len*len));
printf("內切圓對正方形覆蓋率:%lf%%\n",s2/s1*100);
return?0;
}