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<?php $regex = '#[\-\d]$#'; $regex2 = '#[\\-\d]$#'; $regex3 = '#[\\\-\d]$#'; $value = '12-4'; preg_match($regex, $value, $matches); var_dump($matches); preg_match($regex2, $value, $matches); var_dump($matches); preg_match($regex3, $value, $matches); var_dump($matches);
Output for 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.31, 8.3.0 - 8.3.31, 8.4.1 - 8.4.22, 8.5.0 - 8.5.7
array(1) { [0]=> string(1) "4" } array(1) { [0]=> string(1) "4" } Warning: preg_match(): Compilation failed: invalid range in character class at offset 6 in /in/HOedn on line 15 array(1) { [0]=> string(1) "4" }
Output for 7.3.0 - 7.3.33
array(1) { [0]=> string(1) "4" } array(1) { [0]=> string(1) "4" } array(0) { }
Output for 7.2.0 - 7.2.33
array(1) { [0]=> string(1) "4" } array(1) { [0]=> string(1) "4" } Warning: preg_match(): Compilation failed: invalid range in character class at offset 5 in /in/HOedn on line 15 array(1) { [0]=> string(1) "4" }

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