PHP preg_match with working regex [duplicate]

Question

This question already has an answer here:

• Validate date format in php 7 answers

function validateDate( $date )
{ 
    echo $date;
    //2012-08-24 20:30:00
    if(preg_match('/^([0-9]{4})-([0-9]{2})-([0-9]{2}) ([1-2]{1})([0-9]{1}):([0-5]{1})([0-9]{1}):([0-5]{1})([0-9]{1})$/', $date) >= 1)
    {
        return true;
    }
    else
    {
        return false;
    }
}

This always returns false. I used an only tool to build the regular expression and it was working fine there. Trouble started when I added the "/" to the regex. Somehow PHP seems to require these but I dont know why and I dont know why it breaks my regex.

It should return TRUE for sth. like "2012-08-24 20:30:00" and FALSE for "asdf2012-08-24 20:30:00asdf" or anything thats not acording to my regex

Thanks in advance!

-----------------------EDIT Thanks for all your answers!

As some users pointed out my function returns true for the sample date "2012-08-24 20:30:00". However it does that only if i manually set $date='2012-08-24 20:30:00'. If i call the function elsewhere in my code with the exact same string it returns false. Does anyone know why?

-----------------------EDIT2

Yea sorry for wasting your time, it was in fact some whitespace that was added to the string. using trim() on my date before calling my function gives the correct result now.

thanks everyone!

Answer 1

Returns true for me. Try this regex instead:

function validateDate($date) {
  echo $date;
  if( !preg_match("/^(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2})$/",$date,$m)) return false;
  if( !checkdate($m[1],$m[2],$m[0])) return false;
  if( $m[3] > 23) return false;
  if( $m[4] > 59) return false;
  if( $m[5] > 59) return false;
  return true;
}

It is easier to validate format in RegEx, followed by validating content with targeted functions, than to try and do everything in RegEx.

Answer 2

This should work better, and be more simply written:

function validateDate($date)
{
  return preg_match('/^([0-9]{4})-([0-9]{2})-([0-9]{2}) ([1-2]{1})([0-9]{1}):([0-5]{1})([0-9]{1}):([0-5]{1})([0-9]{1})$/', $date);
}

However it will return true with 9999-99-99 29:59:59 as others mentioned...

From PHP manual, you can easily find more elegant and reliable solutions, for example (inspired from this comment):

function validateDate($data)
{
    return (date('Y-m-d H:i:s', strtotime($data)) == $data);
}

Answer 3

What you are asking about are the delimiters. Read this article in PHP.net's manual: RegExp - Delimiters

When using the PCRE functions, it is required that the pattern is enclosed by delimiters. A delimiter can be any non-alphanumeric, non-backslash, non-whitespace character.

And:

Often used delimiters are forward slashes (/), hash signs (#) and tildes (~). The following are all examples of valid delimited patterns.

Answer 4

Why use regex? Use DateTime class.

function validateDate($date, $format = 'Y-m-d H:i:s')
{
    $d = DateTime::createFromFormat($format, $date);
    return $d && $d->format($format) == $date;
}

You can use this function for all kind of date/time validations. Examples:

var_dump(validateDate('2012-02-28 12:12:12')); # true
var_dump(validateDate('2012-02-30 12:12:12')); # false
var_dump(validateDate('2012-02-28', 'Y-m-d')); # true
var_dump(validateDate('28/02/2012', 'd/m/Y')); # true
var_dump(validateDate('30/02/2012', 'd/m/Y')); # false
var_dump(validateDate('14:50', 'H:i')); # true
var_dump(validateDate('14:77', 'H:i')); # false
var_dump(validateDate(14, 'H')); # true
var_dump(validateDate('14', 'H')); # true

var_dump(validateDate('2012-02-28T12:12:12+02:00', 'Y-m-d\TH:i:sP')); # true
# or
var_dump(validateDate('2012-02-28T12:12:12+02:00', DateTime::ATOM)); # true

var_dump(validateDate('Tue, 28 Feb 2012 12:12:12 +0200', 'D, d M Y H:i:s O')); # true
# or
var_dump(validateDate('Tue, 28 Feb 2012 12:12:12 +0200', DateTime::RSS)); # true
var_dump(validateDate('Tue, 27 Feb 2012 12:12:12 +0200', DateTime::RSS)); # false
# ...