这个us namespace std开头就是为了防止名字冲突,有四个循环第一个定义一个数组然后定义数组数的大小，然后里面各种赋值左移右移然后循环判定，比如学校人员统计系统。(The US namespace STD begins with force, and prevents the name from suddenly occurring. There are four cycles, which define the size of an array and array. Then the various assignments are shifted to the left and then move to the right hand.)