//面積
double area(double len,double wid){ return len * wid;}
//周長
雙圓(double len,double wid){ return 2 *(len+wid);}
//對角線
double duijaoxian(double len,double wid){ return sqrt(len * len+wid * wid);}
void main()
{
Printf("請輸入長度和寬度:\ n ");
雙倍長度、寬度;
scanf("%f%f ",& amp長度& amp寬度);
Printf ("area: \n ",面積(長度,寬度));
Printf("圓周:\n ",圓(長,寬));
Printf("對角線長度:\n ",對角線(長度,寬度));
}