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<?php $regex = '#([a-zA-z ])\1{2,}$#'; $string = 'rrrr'; preg_match($regex, $string, $matches); var_dump($matches);
Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.34, 8.3.0 - 8.3.35, 8.4.1 - 8.4.26, 8.5.0 - 8.5.11
array(2) { [0]=> string(4) "rrrr" [1]=> string(1) "r" }

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29.04 ms | 1152 KiB | 7 Q