php error preg_match Unknown modifier '2'

Question

i not understandy i am getting the error preg_match(): Unknown modifier '2' here is my code i trying to parse the audio format.

/**
 * @param string $name
 * @return string|null
 */
public static function parseAudioFormat(string $name): ?string
{
    $Audios = ['AAC', 'AC-3', 'DTS', 'DTS-HD Master Audio', 'DTS-ES', 'DTS 96/24', 'E-AC-3', 'FLAC', 'MP2', 'MP3', 'Opus', 'PCM', 'TrueHD', 'Atmos', 'Vorbis'];
    foreach ($Audios as $audio) {
        if (preg_match("/\b($audio)\b/i", $name, $m)) {
            return $m[0];
        }

    }
    return false;
}

Through the power of substitution :: f($audio)= "/\b($audio)\b/i", f(DTS 96/24)= "`/`\b(DTS 96`/`24)\b`/`i" ,, we see that it is not a metachar problem, but a delimiter problem. — , Oct 02 '20 at 23:13

score 0 · Answer 1 · answered Oct 02 '20 at 23:01

0

This is because you are using what are called meta-characters in your search strings and must be escaped in order to be used literally.

answered Oct 02 '20 at 23:01

Matthew Anderson

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score 0 · Accepted Answer · answered Oct 02 '20 at 23:03

0

The forward slash needs to be escaped ('DTS 96/24').

You can do it automatically using preg_quote() :

foreach ($Audios as $audio) {
    if (preg_match("/\b(" . preg_quote($audio) . ")\b/i", $name, $m)) {
        return $m[0];
    }

}

answered Oct 02 '20 at 23:03

Cid

14,968
4
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The dashes also need to be escaped, but yes, `preg_quote` will do the trick for those too – Matthew Anderson Oct 02 '20 at 23:05
@MatthewAnderson not necessary, they are out of character class actually – Cid Oct 03 '20 at 10:31

php error preg_match Unknown modifier '2'

2 Answers2