<?php
    // 变量：值随时可变，弱类型语言
        // 传值赋值
        // $a = "我要自学";
        // $b = $a;
        // $a = "www.hrkkid.com";
        
        // 传址赋值
        $a = "我要自学";
        $b = &$a;
        $a = "www.hrkkid.com";
        
        echo $a;
        echo "<br>";
        echo $b;
?>