is_string()
(PHP 4, PHP 5, PHP 7)
检测变量是否是字符串
描述
is_string(mixed $var): bool
如果$var是string则返回TRUE
,否则返回FALSE
。
参见is_bool()、is_int()、is_integer()、is_float()、is_real()、is_object()和is_array()。
Using is_string() on an object will always return false (even with __toString()). <?php class B { public function __toString() { return "Instances of B() can be treated as a strings!\n"; } } $b = new B(); print($b); //Instances of B() can be treated as a strings! print(is_string($b) ? 'true' : 'false'); //false ?>
As noted earlier, is_string() returns false on an object that has a __toString() method. Here is a simple way to do a check that will work: <?php // determine if the passed argument can be treated like a string. function is_stringy($text) { return (is_string($text) || (is_object($text) && method_exists($text, '__toString' )); }