问简单的生日系统(PHP / MySQL)有问题

EN

    /*
    *
    * Dates ($dob) can appear as followed:
    * 01-30-2016 | 1-30-2016 | 01-01-2016 | 01/30/2016 or any combination
    *
    */

    $chpos = 0;         // Define Character Position Variable
    $replace = false;   // Should we replace the 0 after the first dash?

    // If the date uses this format: 01/02/2016 then replace the / with - so it looks like 01-02-2016
    $dob = preg_replace('/\s+/', '-', $dob);

    // Let's find out if the dash occurs on the 3rd character or 4th. We do this so we can replace the 0 in 2-02-2016
    // 01-34-6789 *String Array positions* 0-23-5678
    if(substr($dob, 0, 3) == 0 && substr($dob, 0, 0) == 0){
        $chpos = 3;
        $replace == true;
    } else if (substr($dob, 0, 0) != 0 && substr($dob, 0, 2) == 0){
        $chpos = 2;
        $replace == true;
    } else {
        $replace == false;
    }

    // Let's replace the 0 after the first dash if necessary
    if($replace == true){
        $dob = substr_replace($dob, '', $chpos);
    }

    // Let's replace the 0 from the beginning if necessary
    if(substr($dob, 0, 1 ) == 0){
       $dob = substr( $dob, 1 );
    }

    // Let's convert it to a usable date object       
    $birthday = new DateTime($dob);

    // Now let's compare the time from now to when the birthdate happened
    $interval = $birthday->diff(new DateTime);

    // Return the data over
    return $interval->y;

 Uncaught exception 'Exception' with message 'DateTime::__construct(): Failed to parse time string (2-17-1994) at position 0 (2): Unexpected character'