php--异常处理try-catch捕获异常

<?php

function chknum($number)
{
    if ($number >1)
    {
        throw new Exception('value must under 1.');  //主动抛出异常
    }
}

try
{
    chknum(3);
    echo "无任何异常。"."<br>";  //正常状态下
}
catch (Exception $ex)
{
    echo "异常信息：".$ex->getMessage()."<br>";   //捕获异常，显示异常信息
}