PHP: convert date string to Unix timestamp

Look at strtotime, strptime or the DateTime class.

strtotime Example:

$timestamp = strtotime('1/1/2011');

Each function has it's caveat. For instance, the documentation for strtotime states that:

Dates in the m/d/y or d-m-y formats are disambiguated by looking at the separator between the various components: if the separator is a slash (/), then the American m/d/y is assumed; whereas if the separator is a dash (-) or a dot (.), then the European d-m-y format is assumed.

You could also use preg_match to capture all 3 parts and create your own timestamp using mktime.

preg_match Example:

if ( preg_match('/^(?P<day>\d+)[-\/](?P<month>\d+)[-\/](?P<year>\d+)$/', '1/1/2011', $matches) )
{
  $timestamp = mktime(0, 0, 0, ( $matches['month'] - 1 ), $matches['day'], $matches['year']);
}

$to='23.1.2014-18:16:35'
list($part1,$part2) = explode('-', $to);
list($day, $month, $year) = explode('.', $part1);
list($hours, $minutes,$seconds) = explode(':', $part2);
$timeto =  mktime($hours, $minutes, $seconds, $month, $day, $year);
echo $timeto;

You're probably looking for strtotime function.

However just as a caution it will convert each and every possible string format to a unix timestamp (epoch) since it is very difficult to unambiguously parse each and every string to date-time.