sprintf outcome problem

Question

Here is my code:

<?php
$variable1 = 00001;
$variable2 = (sprintf('%04d', $variable1 + 1));
echo $variable2;
?>

How come the outcome of this code is "0002" and not "00002"? in other words it is missing a 0.

Answer 1

The 4 in %04d sets the total width of the printed value

Answer 2

the number in the first parameter is the "total number of characters" not the number of zeroes to use in padding. What you are looking for is %05d instead.

Answer 3

A more interesting question is why does the following print '0009' instead of '0011'?

<?php
$var = 0010;
$str = sprintf('%04d', $var+1);
echo $str;
?>

So why are you using octal representation anyway? I'm just curious.