How do I use current date to minus timestamp to get reminding days?

I want to get a reminding day left using tim开发者_JS百科estamp and current date. Was wondering if I can do a simple subtraction using those.

How do I calculate the currentdate -timestamp?

PHP's timestamps are identical to a Unix timestamp - seconds since Jan 1 1970. So yeah, a simple subtraction will give you a time difference in seconds, which you can convert to days by diving by 86,400 (seconds in a day):

$days = (time() - $oldtimestamp) / 86400;

There is also the, preferred, option of using the DateTime and DateInterval classes.

$now  = new DateTime;
$then = new DateTime;
$then->setTimestamp($timestamp);

$diff = $now->diff($then);
echo $diff->days;

The above will also make available the number of years, months, days, etc. should those be of interest to you (as well as the total number of days as shown).

Try this:

// Will return the number of days between the two dates passed in 
function count_days( $a, $b ) 
{ 
    // First we need to break these dates into their constituent parts: 
    $gd_a = getdate( $a ); 
    $gd_b = getdate( $b ); 
    // Now recreate these timestamps, based upon noon on each day 
    // The specific time doesn't matter but it must be the same each day 
    $a_new = mktime( 12, 0, 0, $gd_a['mon'], $gd_a['mday'], $gd_a['year'] ); 
    $b_new = mktime( 12, 0, 0, $gd_b['mon'], $gd_b['mday'], $gd_b['year'] ); 
    // Subtract these two numbers and divide by the number of seconds in a 
    // day. Round the result since crossing over a daylight savings time 
    // barrier will cause this time to be off by an hour or two. 
    return round( abs( $a_new - $b_new ) / 86400 ); 
} 

Answer courtesy of the Doc