ctype_digit

Check for numeric character(s)

ctype_digit ( mixed $text ) : bool

text

The tested string.

Note: If an integer between -128 and 255 inclusive is provided, it is interpreted as the ASCII value of a single character (negative values have 256 added in order to allow characters in the Extended ASCII range). Any other integer is interpreted as a string containing the decimal digits of the integer.

Returns TRUE if every character in the string text is a decimal digit, FALSE otherwise.

<?

$text = "0123456789";

$return = ctype_digit($text);

var_export($return);

?>

true

<?

for ($i = 0; $i <= 255; ++$i)
{
    $return = ctype_digit($i);

    if ($return)
    {
        $character = chr($i);

        echo "$i: $character\n";
    }
}

?>

48: 0
49: 1
50: 2
51: 3
52: 4
53: 5
54: 6
55: 7
56: 8
57: 9

PHP