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(PHP 4, PHP 5)
is_string — Prüft, ob Variable vom Typ string ist
Die zu untersuchende Variable.
Gibt TRUE zurück, wenn var vom Typ string ist, andernfalls FALSE.
Beispiel #1 is_string()-Beispiel
<?php
if (is_string("23")) {
echo "is string\n";
} else {
echo "is not an string\n";
}
var_dump(is_string('abc'));
var_dump(is_string("23"));
var_dump(is_string(23.5));
var_dump(is_string(true));
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
is string bool(true) bool(true) bool(false) bool(false)
Be aware that this function could result into unwanted results if you check single chars in an array.
For instance:
You have a simple string and want to repeat this string evertime it ends.
<?php
for ($i=0; $i < strlen($string);$i++){
if(!is_string($key[$x]))
$x = 0;
echo $key[$x];
$x++;
}
?>
This will print you out the key, but won't iterate it since $x won't be reset. is_string function will give out true at element in that string, even if it doesn't exist. for instance is_string $key[1000] while your string is just 10chars long.
However this doesn't matter just use $key[$x] == '' instead.
Of course you won't use this to iterate a string, but you might come across something where this get useful, for instance for a en/decrypt engine.
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