(PHP 4, PHP 5, PHP 7, PHP 8)
is_string — Verifica se il tipo di una variabile sia stringa
varLa variabile da valutare.
Example #1 Esempio di is_string()
<?php
$values = array(false, true, null, 'abc', '23', 23, '23.5', 23.5, '', ' ', '0', 0);
foreach ($values as $value) {
echo "is_string(";
var_export($value);
echo ") = ";
echo var_dump(is_string($value));
}
?>Il precedente esempio visualizzerà:
is_string(false) = bool(false)
is_string(true) = bool(false)
is_string(NULL) = bool(false)
is_string('abc') = bool(true)
is_string('23') = bool(true)
is_string(23) = bool(false)
is_string('23.5') = bool(true)
is_string(23.5) = bool(false)
is_string('') = bool(true)
is_string(' ') = bool(true)
is_string('0') = bool(true)
is_string(0) = bool(false)
Using is_string() on an object will always return false (even with __toString()).<?phpclass 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' ));}Missing in example :<?echo var_dump(is_string([]));?>bool(false)