求C语言编程矩形面积周长对角线

#include "stdio.h"
//面积
double area(double len,double wid){return len*wid;}
//周长
double circle(double len,double wid){return 2*(len+wid);}
//对角线
double duijiaoxian(double len,double wid){return sqrt(len*len+wid*wid);}
void main()
{
printf("请输入长宽：\n");
double length,width;
scanf("%f%f",&length,&width);
printf("面积为：\n",area(length,width));
printf("周长为：\n",circle(length,width));
printf("对角线长为：\n",duijiaoxian(length,width));
}