关于isset的一点说明

作者：zhanhailiang 日期：2014-10-08

<?

php
$a = 'abc';
var_dump(isset($a['code'])); // 理论上应该是False，可是确是TRUE

Example #2 isset() on String Offsets

PHP 5.4 changes how isset() behaves when passed string offsets.

<?

php
$expected_array_got_string = 'somestring';
var_dump(isset($expected_array_got_string['some_key']));
var_dump(isset($expected_array_got_string[0]));
var_dump(isset($expected_array_got_string['0']));
var_dump(isset($expected_array_got_string[0.5]));
var_dump(isset($expected_array_got_string['0.5']));
var_dump(isset($expected_array_got_string['0 Mostel']));
?>
Output of the above example in PHP 5.3:

bool(true)
bool(true)
bool(true)
bool(true)
bool(true)
bool(true)
Output of the above example in PHP 5.4:

bool(false)
bool(true)
bool(true)
bool(true)
bool(false)
bool(false)

<?php

$a = 'abc';
var_dump(is_array($a) && isset($a['code']));