C primer plus (第六版）第九章 编程练习第6题

题目：

6.编写并测试一个函数，该函数以3个double变量的地址作为参数，把最小值放入第1个函数，中间值放入第2个变量，最大值放入第3个变量。

思路：用2个浮点数比较大小的函数比较三次完成排序，直接用本章指针函数的示例来做；

#include <stdio.h>
void arrange_two(double * x, double * y);           //两个浮点数比较大小的函数
int main()
{double a, b, c;printf("Please entry three float numbers:\n");while (scanf("%lf, %lf, %lf", &a, &b, &c) == 3){printf("Entered float numbers are %.3lf; %.3lf; %.3lf;\n",a,b,c);           //未排序前输入的浮点数arrange_two(&a, &b);arrange_two(&b, &c);arrange_two(&a, &b);printf("After arrange from low to large: %.3lf; %.3lf; %.3lf;\n",a,b,c);    //排序后打印printf("Please entry another three float numbers:\n");                      //循环提示输入，非浮点数退出}printf("Done!.\n");return 0;
}void arrange_two(double * x, double * y)
{double temp;if (*x > *y){temp = *x;*x = *y;*y = temp;}
}