正则表达式子串的长度

Question

I receive a string conformed by numbers and points. I need those numbers to have a minimum length of 3, so, I have to add one or more zeros in from of the numbers with a lower length.

Example:

If I have:

233.14.205.1.194056.270132

I need it to be:

233.014.205.001.194056.270132
    ↑       ↑↑

(Note the 014 where there was a 14 and the 001 where there was a 1)

I know I can explode the string, add the zeros I need and implode it again, but I want not to create a function for something that can solved with a native function (preg_replace) and I am not very good with regex (yet).

Answer 1

Using explode -> zero padding -> implode will indeed be straight forward.

Since you're specifically asking for preg_replace way of doing it here it is:

$s = '233.14.205.1.194056.270132'

$repl = preg_replace(array('/\b\d\b/', '/\b\d\d\b/'), array('00$0', '0$0'), $s);
//=> 233.014.205.001.194056.270132

Here we're passing a 2 element array of regex to preg_replace and inserting singe or double zeroes before the matched double/single digit.