Question

I have this string

$string = "some words and then #1.7 1.7 1_7 and 1-7";

and I would like that #1.7/1.7/1_7 and 1-7 to be replaced by S1E07.
Of course, instead of “1.7” is just an example, it could be “3.15” for example.

I managed to create the regular expression that would match the above 4 variants

/\#\d{1,2}\.\d{1,2}|\d{1,2}_\d{1,2}|\d{1,2}-\d{1,2}|\d{1,2}\.\d{1,2}/

but I cannot figure out how to use preg_replace (or something similar?) to actually replace the matches so they end up like S1E07

Answer 1

You need to use preg_replace_callback if you need to pad 0 if the number less than 10.

$string = "some words and then #1.7 1.7 1_7 and 1-7";
$string = preg_replace_callback('/#?(\d+)[._-](\d+)/', function($matches) {
  return 'S'.$matches[1].'E'.($matches[2] < 10 ? '0'.$matches[2] : $matches[2]);
}, $string);