$a = 'link';
$b = 'module';
var_dump( isset( $a[ $b ] ) );
怎么是true,这是怎么算的
不同版本的 PHP 下是不一样的,参见 http://3v4l.org/VgOpW
Output for 5.0.0 - 5.0.2, 5.4.0 - 5.5.6
bool(false)
Output for 4.3.0 - 4.4.9, 5.0.3 - 5.3.27
bool(true)
所以,还是不要这么用吧。
你加两行代码:
原因:
如果你希望它返回false,你应该这么写:
参考资料:
> Internally, PHP strings are byte arrays. As a result, accessing or modifying a string using array brackets is not multi-byte safe, and should only be done with strings that are in a single-byte encoding such as ISO-8859-1.
来源:http://www.php.net/manual/en/language.types.string.php#language.types.string.substr
> If the string starts with valid numeric data, this will be the value used. Otherwise, the value will be 0 (zero)
来源:http://www.php.net/manual/en/language.types.string.php#language.types.string.conversion