方法1：使用变量，使得两个数交换，代码如下

#include<stdio.h>

int main()
{
  int a = 3;
  int b = 5;
  int tmp = 0;
  printf("before:a=%d,b=%d\n", a, b);
  tmp = a;
  a = b;
  b = tmp;
  printf("after: a=%d,b=%d\n", a, b);
  return 0;
}

方法2：使用加减法实现两个数的交换，代码如下​【缺陷：可能会溢出】​

#include<stdio.h>

int main()
{
  int a = 3;
  int b = 5;
  printf("before:a=%d,b=%d\n", a, b);
  a = a + b;
  b = a - b;
  a = a - b;
  printf("after: a=%d,b=%d\n", a, b);
  return 0;
}

方法3：使用异或法实现两个数的交换，代码如下

#include<stdio.h>

int main()
{
  int a = 3;
  int b = 5;
  printf("before:a=%d,b=%d\n", a, b);
  a = a ^ b;
  b = a ^ b;
  a = a ^ b;
  printf("after: a=%d,b=%d\n", a, b);
  return 0;
}