preg_match错误未知修饰符'（'[重复]

Question

This question already has an answer here:

• Warning: preg_replace(): Unknown modifier ']' 3 answers

What's wrong with this?

public static function validaDataHoraBR($data_hora){
  $pattern = "/^([1-9]|0[1-9]|[1,2][0-9]|3[0,1])/([1-9]|1[0,1,2])/\d{4} ([0-1][0-9]|[2][0-3])(:([0-5][0-9])){1,2}(:([0-5][0-9])){1,2}$/";
  return (preg_match($pattern, $data_hora)) ? array(true) : array(false,' não é uma data e hora no formato BR!<br>'); 
}

This pattern validate this - 20/08/2011 21:00:00

Error: Message: preg_match() [function.preg-match]: Unknown modifier '('

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Answer 1

Escape / in the regular expression.

"/^([1-9]|0[1-9]|[1,2][0-9]|3[0,1])\/([1-9]|1[0,1,2])\/\d{4} ([0-1][0-9]|[2][0-3])(:([0-5][0-9])){1,2}(:([0-5][0-9])){1,2}$/"
#                                   ^                 ^

Otherwise, / is recognised as end of the regular expression.

Or use different delimiters:

"#^([1-9]|0[1-9]|[1,2][0-9]|3[0,1])/([1-9]|1[0,1,2])/\d{4} ([0-1][0-9]|[2][0-3])(:([0-5][0-9])){1,2}(:([0-5][0-9])){1,2}$#"