bool ctype_alnum ( string $text )

<?php var_dump(ctype_alnum(-1));
// UNIX: bool(false)
// Windows: bool(true)

ctype_alnum() example (using the default locale)

<?php
$strings = array('AbCd1zyZ9', 'foo!#$bar');
foreach ($strings as $testcase) {
    if (ctype_alnum($testcase)) {
        echo "The string $testcase consists of all letters or digits.\n";
    } else {
        echo "The string $testcase does not consist of all letters or digits.\n";
    }
}
?>

The above example will output:

The string AbCd1zyZ9 consists of all letters or digits.
The string foo!#$bar does not consist of all letters or digits.

It is possible to use the dedicated function, ctype_alnum to check whether it is an alphanumeric value or not.

It is possible to use the dedicated function, ctype_alnum to check whether it is an alphanumeric value or not.