异或运算^的一个作用
交换两个整数的值而不必用第三个参数
a = 9;
b = 11;
a=a^b; 1001^1011=0010
b=b^a; 1011^0010=1001
a=a^b; 0010^1001=1011
a = 11;
b = 9;
a = 9;
b = 11;
a=a^b; 1001^1011=0010
b=b^a; 1011^0010=1001
a=a^b; 0010^1001=1011
a = 11;
b = 9;
Life is a journey, not a destination.