加法实现：

#include <stdio.h>

int main()

{

    int a = 30;

    int b = 20;

    a = a + b;

    b = a - b;

    a = a - b;

    printf("a=%d,b=%d\n", a, b);

    return 0;

}

乘法实现：

#include <stdio.h>

int main()

{

    int a = 30;

    int b = 20;

    a = a * b;

    b = a / b;

    a = a / b;

    printf("a=%d,b=%d\n", a, b);

    return 0;

}*/

按位异或法实现：

#include <stdio.h>

int main()

{

    int a = 30;

    int b = 20;

    a = a ^ b;

    b = a ^ b;

    a = a ^ b;

    printf("a=%d,b=%d\n", a, b);

}

总结：加法与乘法中, 虽然节省了时间, 但是当参加运算的两个数比较大的,

有时候加1就会发生溢出; 而按位异或法则防止了溢出情况, 按位异或法:

(mod 2)相同为1, 不同为0