变量转换（不使用中间变量）

第一种方法：

a=a+b;

b=a-b;

a=a-b;

代码如下：

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1. #include"stdio.h"
2. intmain(void)
3. {
4. inta,b;
5. printf("请输入两个变量a和b：/n");
6. scanf("%d%d",&a,&b);
7. printf("a和b交换前：/n");
8. printf("a=%db=%d/n",a,b);
9. a=a+b;
10. b=a-b;
11. a=a-b;
12. printf("a和b交换后：/n");
13. printf("a=%db=%d/n",a,b);
14. system("pause");
15. return0;
16. }

缺点：可能越界

第二种方法：

解决方法：（a、b异或的结果，和a异或得b，和b异或得a）

a=a^b；

b=a^b；

a=a^b；

代码如下：

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1. #include"stdio.h"
2. intmain(void)
3. {
4. inta,b;
5. printf("请输入两个变量a和b：/n");
6. scanf("%d%d",&a,&b);
7. printf("a和b交换前：/n");
8. printf("a=%db=%d/n",a,b);
9. a=a^b;
10. b=a^b;
11. a=a^b;
12. printf("a和b交换后：/n");
13. printf("a=%db=%d/n",a,b);
14. system("pause");
15. return0;
16. }

写成宏替换的方法如下：

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1. #include"stdio.h"
2. #defineswap(a,b)(a)^=(b)^=(a)^=(b)
3. intmain(void)
4. {
5. inta,b;
6. printf("请输入两个变量a和b：/n");
7. scanf("%d%d",&a,&b);
8. printf("a和b交换前：/n");
9. printf("a=%db=%d/n",a,b);
10. swap(a,b);
11. printf("a和b交换后：/n");
12. printf("a=%db=%d/n",a,b);
13. system("pause");
14. return0;
15. }