Regex to grab Date from String

Question

I'm trying to grab part of a string that represents a date.

The date-string will usually, but not always, have regular text before and/or after it.

In this example:

Sometimes text is here, Sun, Apr 09, 2000  And sometimes but not always text here

I would want the result to be:

Sun, Apr 09, 2000

Bear in mind that days and month strings can be 3 or 4 characters in length.

My meager attempt is:

$test = "Sometimes text is here, Sun, Apr 09, 2000  And sometimes but not always text here";

if (ereg ("/([a-z]{3,4}),.([a-z]{3,4}).([0-9]{1,2}),.([0-9]{4})/i", $test, $regs)) {
    echo "$regs[4].$regs[3].$regs[2].$regs[1]";
}

Also interested in hearing non-regex based solutions.

2 revs · Accepted Answer · 2012-01-21 21:40:38Z

Someone could probably do better than this as it's pretty verbose:

/(?:mon|tues?|weds|thurs?|fri|sat|sun), [a-z]{3,4} [0-9]{1,2}, [0-9]{4}/i

$regex = '/(?:mon|tues?|weds|thurs?|fri|sat|sun), [a-z]{3,4} [0-9]{1,2}, [0-9]{4}/i';
$string = 'Sometimes text is here, Sun, Apr 09, 2000  And sometimes but not always text here';

preg_match($regex, $string, $matches);

echo $matches[0];
// Sun, Apr 09, 2000

If you're expecting the date to occur multiple times, a minor change helps.

// store the match as a named parameter called 'date'
$regex = '/(?<date>(?:sun|mon|tues?|weds|thurs?|fri|sat|sun), [a-z]{3,4} [0-9]{1,2}, [0-9]{4})/i';

$string = 'Sometimes text is here, Sun, Apr 09, 2000  And sometimes but not always text here. Sun, Mar 10, 2010';

preg_match_all($regex, $string, $matches);

print_r($matches['date']);
/* 
 Array
    (
        [0] => Sun, Apr 09, 2000
        [1] => Sun, Mar 10, 2010
    )
*/

Started off with the name of the day, just on the off chance you get something that looks the same as a day but isn't.

I'd also not suggest using ereg() as it was deprecated in 5.3.0. Use preg_match() instead, or one of the other preg_* functions.

drew010 · Accepted Answer · 2012-01-21 21:28:39Z

1

This regex seems to work in multiple cases:

$str = "Sometimes text is here, Sun, Apr 09, 2000  And sometimes but not always text here";
$reg = '/(\w{3}),\s*(\w{3})\s*(\d+),\s*(\d{4})/';

$match = preg_match($reg, $str, $matches);

if ($match) {
    $date = "{$matches[2]} {$matches[3]} {$matches[4]}\n";
    // Apr 09 2000
    $timestamp = strtotime($date);
}

ereg() should no longer be used, as of PHP 5.3.0 it is deprecated and preg has long been favored as a faster, more widely used alternative.

answered Jan 21, 2012 at 21:28

drew010

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Comments

Josh · Accepted Answer · 2012-01-21 21:30:09Z

1

Instead of relying on deprecated ereg, try preg_match_all.

$str = "Sometimes text is here, Sun, Apr 09, 2000  And sometimes but not always text here";

preg_match_all('/.*([A-Za-z]{3,4}, [A-Za-z]{3,4} [\d]{1,2}, [\d]{4}).*/',$str,$matches);

Output

(
    [0] => Array
        (
            [0] => Sometimes text is here, Sun, Apr 09, 2000  And sometimes but not always text here
        )

    [1] => Array
        (
            [0] => Sun, Apr 09, 2000
        )

)

You'll find all matches in $matches[1].

answered Jan 21, 2012 at 21:30

Josh

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