假设 a、b 两个数字，有很多方法不使用第三个变量交换两个数字的值。

方法1(使用算术运算符)：

#include <stdio.h>
int main()
{
    int a = 10, b = 5;
    // algo to swap 'a' and 'b'
    a = a + b;  // a becomes 15
    b = a - b;  // b becomes 10
    a = a - b;  // fonally a becomes 5
    printf("After Swapping the value of: a = %d, b = %d

", a, b);
    return 0;
}

方法2(使用按位异或运算符)：

#include <stdio.h>
int main()
{
    int a = 10, b = 5;
    // algo to swap 'a' and 'b'
    a = a ^ b;  // a becomes (a ^ b)
    b = a ^ b;  // b = (a ^ b ^ b), b becomes a
    a = a ^ b;  // a = (a ^ b ^ a), a becomes b
    printf("After Swapping the value of: a = %d, b = %d

", a, b);
    return 0;
}