Regular expressions doesn't change any text in PHP - php

Question

I have this code to replace every number (and point) and replace it by <b>and the text</b>
<?
function reem2($cadena) {
$buscarRegex = array('/^([0-9]{1}|[.])$/i');
$reemplazo = array('<b>$i</b>');
$mag = preg_replace($buscarRegex, $reemplazo, $cadena);
return $cadena;
}
$string = "1. Krewella - Can't Control Myself
2. Kdrew - Circles
3. Korn Feat. Skrillex & Kill The Noise - Narcissistic Cannibal
4. Netsky - Love Has Gone
5. Example - Midnight Run (Flux Pavilion Remix)
6. Madeon - Finale (Radio Version)
7. Feed Me Vs. Knife Party Vs. Skrillex - My Pink Reptile Party (Maluu's Slice'n'diced Mashup)
8. Krewella & Pegboard Nerds - This Is Not The End
9. Skrillex - Bangarang
10. The Prototypes - Suffocate
11. Ayah Marar - Mind Controller (Cutline Remix)
12. Skrillex Feat. Krewella - Breathe (Vocal Edit)
13. Utah Saints Vs. Drumsound & Bassline Smith - What Can You Do For Me (Tantrum Desire Remix)
14. Nero - Promises (Skrillex & Nero Remix)
15. 20 Florence & The Machine - Cosmic Love (Seven Lions Remix)";
echo reem2(nl2br($string));
?>
But it doesn't work, It doesn't change anything:
The output in HTML would be:
1. Krewella - Can't Control Myself
2. Kdrew - Circles
3. Korn Feat. Skrillex & Kill The Noise - Narcissistic Cannibal
4. Netsky - Love Has Gone
5. Example - Midnight Run (Flux Pavilion Remix)
6. Madeon - Finale (Radio Version)
7. Feed Me Vs. Knife Party Vs. Skrillex - My Pink Reptile Party (Maluu's Slice'n'diced Mashup)
8. Krewella & Pegboard Nerds - This Is Not The End
9. Skrillex - Bangarang
10. The Prototypes - Suffocate
11. Ayah Marar - Mind Controller (Cutline Remix)
12. Skrillex Feat. Krewella - Breathe (Vocal Edit)
13. Utah Saints Vs. Drumsound & Bassline Smith - What Can You Do For Me (Tantrum Desire Remix)
14. Nero - Promises (Skrillex & Nero Remix)
15. 20 Florence & The Machine - Cosmic Love (Seven Lions Remix)
What can I do?

Answer 1

Your regex is broken:
/^([0-9]{1}|[.])$/i
^-- start of line
^--- end of line
you are allowing only for one SINGLE character on a line by itself, so the regex can never match anything.
You probably want something more like this:
/^([\d]+)\./
which will match any number of digits at the start of the line, which are followed by a single ..

Answer 2

You may use the following code:
function reem2($cadena) {
$buscarRegex = array('/^(\d+\.)/mi'); // This means match any digit(s) followed by a dot at the beginning of each line. Note the m modifier
$reemplazo = array('<b>$1</b>'); // replace should be with group 1, not some vague $i
$mag = preg_replace($buscarRegex, $reemplazo, $cadena);
return $mag; // return value: fixed
}

Answer 3

return $cadena;
is your problem, Your doing the replace and then throwing the result away and returning the input
return $mag;
is probably what you meant
in fact your regex is also wrong
function reem2($cadena) {
$buscarRegex = array('/^([0-9]{1,2}\.)(.*)$/m');
$reemplazo = array('<b>\1</b>\2');
$mag = preg_replace($buscarRegex, $reemplazo, $cadena);
return $mag;
}
seems to be what you want.

Answer 4

So from what I see, your regex is incorrect and you're returning the incorrect variable in function reem2, so try replacing your function with something like this
function reem2($cadena) {
return preg_replace("/([0-9]+\.)/", "<b>$1</b>", $cadena);
}

Answer 5

function reem2($cadena) {
$buscarRegex = array('/^([0-9]+\.)/m'); // changed modifier to multiline
$reemplazo = array('<b>$1</b>'); // changed replacement to a capture offset
return preg_replace($buscarRegex, $reemplazo, $cadena);
}