<?php
//赋值
$some1 = NULL;
$some2 = 0;
$some3 = "";
//0与NULL比较
echo $some1==$some2;
echo "<br />";
//NULL与""比较
echo $some1 == $some3;
echo "<br />";
//0与""比较
echo $some2 == $some3;
?>
输出
1
1
1
说明在php中这3个是等价的。、。。
原文：http://www.cnblogs.com/tumio/p/4535820.html