CODEWITHSUNDEEP
phpregexstringlogic
danijar
danijar

Reputation: 34215

Regex for multiple Consonants

I am looking for a regex pattern I want to use in my php name generator script.

It should detect if the string contains three consecutive consonants. But it should not detect the string if two consecutive consonants of the three consecutive consonants are the same.

Example:

"hello" -> False, because there aren't 3 consecutive consonants.
"matching" -> True, because there are 3 consecutive consonants.
"apple" -> False, although there are 3 consecutive consonants, because two consecutive of them are the same.

Please help me to find such a regex pattern.

Upvotes: 4

Views: 4721

Answers (4)

Sam Greenhalgh
Sam Greenhalgh

Reputation: 6136

(([b-df-hj-np-tv-z])(?!\2)){3}

http://gskinner.com/RegExr/?2vtnt

Edit

There's an edge case with this pattern that it fails if it's proceeded by the same last consonant. E.g xyzz should match xyz but doesn't.

This would be a more accurate pattern. (([b-df-hj-np-tv-z])(?!\2)){2}[b-df-hj-np-tv-z]

Upvotes: 6

ugoren
ugoren

Reputation: 16441

This can be done with a negative assertion and a lookback:
1. Use the lookback to build an expression to match two identical characters: (.)\1.
2. Add .?, before it, to catch the pair either immediately or after a character: .?(.)\1.
3. 3 consecutive consonants: [b-df-hj-np-tv-z]{3}
4. Add #2 above as a negative assertion: (?!.?(.)\1)[b-df-hj-np-tv-z]{3}.

I took some parts from @zapthedingbat's answer, which is more elagant, but (I think) errs a bit.

Upvotes: 2

TimWolla
TimWolla

Reputation: 32701

/([bcdfghjklmnpqrstvwxyz]{3})/i

This will match 3 consonants in a row. And then str_split the match and check whether all three items are different.

preg_match_all('/([bcdfghjklmnpqrstvwxyz]{3})/i', $string, $matches);
foreach ($matches[0] as $match) {
    $items = str_split(strtolower($match));
    if ($items[0] != $items[1] && $items[1] != $items[2]) {
        // match
    }
}

Upvotes: 0

shadyabhi
shadyabhi

Reputation: 17234

This will work.

/([^aeiou]{3})/i

^ in the class means it should NOT comtain a,e,i,o,u

Upvotes: 1

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