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?

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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;

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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).

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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