php的位运算

<?php
switch (1&2) {
case 0:
echo 'First case, with a break';
break;
case 1:
echo 'Second case, which falls through';
case 2:
case 3:
case 4:
echo 'Third case, return instead of break';
return;//注意细节
default:
echo 'Default case';
break;

}

查看结果：First case, with a break

'&'-------位与运算：

0001

0010

——

0000

'|'-------位或运算：

0001

0010

——

0011