string - PHP, str_pad unicode issue

Question

I'm just trying to make fixed the $str to 5 characters, but couldn't.

$str = "nü";
echo str_pad($str, 5, "ü"); // give nüü

I know that's an unicode issue and searched a lot but no luck. I tried somethings such as;

echo str_pad($str, 4 + mb_strlen($s), $s);
echo str_pad($str, 5 + mb_strlen($s), $s);

Also I tried this http://www.php.net/manual/de/function.str-pad.php#89754 and saw this https://stackoverflow.com/a/11871948/362780.

Any experience on this issue?

Thanks.

Answer 1

You need a multibyte version of str_pad(), like below. It's inspired by the source code of str_pad().

function mb_str_pad($input, $pad_length, $pad_string = ' ', $pad_type = STR_PAD_RIGHT, $encoding = 'UTF-8')
{
    $input_length = mb_strlen($input, $encoding);
    $pad_string_length = mb_strlen($pad_string, $encoding);

    if ($pad_length <= 0 || ($pad_length - $input_length) <= 0) {
        return $input;
    }

    $num_pad_chars = $pad_length - $input_length;

    switch ($pad_type) {
        case STR_PAD_RIGHT:
            $left_pad = 0;
            $right_pad = $num_pad_chars;
            break;

        case STR_PAD_LEFT:
            $left_pad = $num_pad_chars;
            $right_pad = 0;
            break;

        case STR_PAD_BOTH:
            $left_pad = floor($num_pad_chars / 2);
            $right_pad = $num_pad_chars - $left_pad;
            break;
    }

    $result = '';
    for ($i = 0; $i < $left_pad; ++$i) {
        $result .= mb_substr($pad_string, $i % $pad_string_length, 1, $encoding);
    }
    $result .= $input;
    for ($i = 0; $i < $right_pad; ++$i) {
        $result .= mb_substr($pad_string, $i % $pad_string_length, 1, $encoding);
    }

    return $result;
}


$str = "nü";
$pad = "ü";

echo mb_str_pad($str, 5, $pad);