How to convert date to timestamp in PHP?

Solution 1:

This method works on both Windows and Unix and is time-zone aware, which is probably what you want if you work with dates.

If you don't care about timezone, or want to use the time zone your server uses:

$d = DateTime::createFromFormat('d-m-Y H:i:s', '22-09-2008 00:00:00');
if ($d === false) {
    die("Incorrect date string");
} else {
    echo $d->getTimestamp();
}

1222093324 _{(This will differ depending on your server time zone...)}

If you want to specify in which time zone, here EST. (Same as New York.)

$d = DateTime::createFromFormat(
    'd-m-Y H:i:s',
    '22-09-2008 00:00:00',
    new DateTimeZone('EST')
);

if ($d === false) {
    die("Incorrect date string");
} else {
    echo $d->getTimestamp();
}

1222093305

Or if you want to use UTC. (Same as "GMT".)

$d = DateTime::createFromFormat(
    'd-m-Y H:i:s',
    '22-09-2008 00:00:00',
    new DateTimeZone('UTC')
);

if ($d === false) {
    die("Incorrect date string");
} else {
    echo $d->getTimestamp();
}

1222093289

Regardless, it's always a good starting point to be strict when parsing strings into structured data. It can save awkward debugging in the future. Therefore I recommend to always specify date format.

Solution 2:

There is also strptime() which expects exactly one format:

$a = strptime('22-09-2008', '%d-%m-%Y');
$timestamp = mktime(0, 0, 0, $a['tm_mon']+1, $a['tm_mday'], $a['tm_year']+1900);

Solution 3:

With DateTime API:

$dateTime = new DateTime('2008-09-22'); 
echo $dateTime->format('U'); 

// or 

$date = new DateTime('2008-09-22');
echo $date->getTimestamp();

The same with the procedural API:

$date = date_create('2008-09-22');
echo date_format($date, 'U');

// or

$date = date_create('2008-09-22');
echo date_timestamp_get($date);

If the above fails because you are using a unsupported format, you can use

$date = DateTime::createFromFormat('!d-m-Y', '22-09-2008');
echo $dateTime->format('U'); 

// or

$date = date_parse_from_format('!d-m-Y', '22-09-2008');
echo date_format($date, 'U');

Note that if you do not set the !, the time portion will be set to current time, which is different from the first four which will use midnight when you omit the time.

Yet another alternative is to use the IntlDateFormatter API:

$formatter = new IntlDateFormatter(
    'en_US',
    IntlDateFormatter::FULL,
    IntlDateFormatter::FULL,
    'GMT',
    IntlDateFormatter::GREGORIAN,
    'dd-MM-yyyy'
);
echo $formatter->parse('22-09-2008');

Unless you are working with localized date strings, the easier choice is likely DateTime.

Solution 4:

Be careful with functions like strtotime() that try to "guess" what you mean (it doesn't guess of course, the rules are here).

Indeed 22-09-2008 will be parsed as 22 September 2008, as it is the only reasonable thing.

How will 08-09-2008 be parsed? Probably 09 August 2008.

What about 2008-09-50? Some versions of PHP parse this as 20 October 2008.

So, if you are sure your input is in DD-MM-YYYY format, it's better to use the solution offered by @Armin Ronacher.

Solution 5: