c语言函数实现交换两个数的值 | 您所在的位置:网站首页 › c语言实现两个数的交换 › c语言函数实现交换两个数的值 |
代码:
1 #include
2
3 void swap(int x,int y)
4 {
5 int temp;
6
7 temp = x;
8 x = y;
9 y = temp;
10 printf("In swap: x = %d,y = %d\n",x,y);
11 }
12
13 void swap_with_pt(int * x,int * y)
14 {
15 int temp;
16
17 temp = *x;
18 *x = *y;
19 *y = temp;
20 printf("In swap_with_pt: x = %d,y = %d\n",*x,*y);
21 }
22
23 int main()
24 {
25 int x = 5,y = 10;
26
27 printf("Before swap: x = %d,y = %d\n",x,y);
28 swap(x,y);
29 printf("After swap: x = %d,y = %d\n",x,y);
30 printf("-------------------------------\n");
31 printf("Before swap_with_pt: x = %d,y = %d\n",x,y);
32 swap_with_pt(&x,&y);
33 printf("After swap_with_pt: x = %d,y = %d\n",x,y);
34
35 return 0;
36 }
输出:
1 Before swap: x = 5,y = 10
2 In swap: x = 10,y = 5
3 After swap: x = 5,y = 10
4 ---------------------------------
5 Before swap_with_pt: x = 5,y = 10
6 In swap_with_pt: x =10,y = 5
7 After swap_with_pt: x = 10,y = 5
解释:
swap函数调用时首先创建x,y的变量副本,我们姑且称之为x2,y2(其实名字依然是x和y,只不过这里的x和y只在swap函数里有意义),并将main函数中x,y的值传给变量x2,y2,然后函数交换了x2,y2的值,运行完函数后x2,y2变量生命期结束。所以,x和y的值是不变的。 swap_with_pt函数调用时同样创建x,y的指针的变量副本,我们姑且称之为x2,y2(其实名字依然是x和y,只不过这里的x和y只在swap_with_pt函数里有意义),并将x,y的地址值传给x2,y2,这个时候x2和y2是指向main函数中x,y的,然后通过*运算修改x,y的值。注意,“*+指针名”是可以改变它所指向的变量的值的。 |
CopyRight 2018-2019 实验室设备网 版权所有 |