Four ways to exchange the values of 2 variables

1. Use the third variable: c=a, a=b, b=c
2. Use 4 variables, give the values ​​of a and b to c and d respectively, and then exchange
3. Just two variables, use Addition/subtraction/division

4, or two variables, use the exclusive OR operation (binary, the same is 0, the difference is 1, that is, the same false but different true)