zerofill a integer php

Question

How would I go about 'zero filling' an integer?

ie

1 becomes 0001
40 becomes 0040
174 becomes 0174

Answer 1

$filled_int = sprintf("%04d", $your_int)

Answer 2

$number = 12;
$width = 4;
$padded = str_pad((string)$number, $width, "0", STR_PAD_LEFT);