无法在PHP中将字符串偏移量用作数组

无法在PHP中将字符串偏移量用作数组 对于PHP4

…这重现了错误：

$foo    = 'bar';$foo[0] = 'bar';

对于PHP5

…这重现了错误：

$foo = 'bar';if (is_array($foo['bar']))    echo 'bar-array';if (is_array($foo['bar']['foo']))    echo 'bar-foo-array';if (is_array($foo['bar']['foo']['bar']))    echo 'bar-foo-bar-array';

（实际上来自bugs.php.net）

编辑，

因此，即使是字符串，为什么错误也不会出现在第一个if条件中。

因为PHP是一种非常宽容的编程语言，所以我猜。我将用代码说明我的想法：

$foo = 'bar';// $foo is now equal to "bar"$foo['bar'] = 'foo';// $foo['bar'] doesn't exists - use first index instead (0)// $foo['bar'] is equal to using $foo[0]// $foo['bar'] points to a character so the string "foo" won't fit// $foo['bar'] will instead be set to the first index// of the string/array "foo", i.e 'f'echo $foo['bar'];// output will be "f"echo $foo;// output will be "far"echo $foo['bar']['bar'];// $foo['bar'][0] is equal calling to $foo['bar']['bar']// $foo['bar'] points to a character// characters can not be represented as an array,// so we cannot reach anything at position 0 of a character// --> fatal error