这个是什么操作符啊?
计算的结果这么奇怪?
            Console.WriteLine("5&6=" + (5 & 6));
            Console.WriteLine("6&2=" + (6 & 2));
            Console.WriteLine("6&5=" + (6 & 5));
            Console.WriteLine("7&5=" + (7 & 5));
结果:5&6=4
6&2=2
6&5=4
7&5=5