php实现用已经过去多长时间的方式显示时间

function time_is_older_than($t, $check_time){
  $t = strtolower($t);
  $time_type = substr(preg_replace(/[^a-z]/, , $t), 0, 1);
  $val = intval(preg_replace(/[^0-9]/, , $t));
  $ts = 0;
  // (s)econds, (m)inutes, (d)ays, (y)ears
  if ($time_type == s){ $ts = $val; }
  else if ($time_type == m){ $ts = $val * 60; }
  else if ($time_type == h){ $ts = $val * 60 * 60; }
  else if ($time_type == d){ $ts = $val * 60 * 60 * 24; }
  else if ($time_type == y){ $ts = $val * 60 * 60 * 24 * 365; }
  else { die(Unknown time format given!); }
  if ($check_time < (time()-$ts)){ return true; }
  return false;
}

//使用范例：
// timestamp to test: 
// (could be from an database or something else)
$time = 1146722922;
// long if check:
if (time_is_older_than(30m, $time)){
  print The given timestamp:  . date(l dS \of F Y h:i:s A,$time);
  print " - is older than 30 minutes<br/>\n";
}
else {
  print The given timestamp:  . date(l dS \of F Y h:i:s A,$time);
  print " - is NOT older than 30 minutes<br/>\n";
}
// short checks:
if (time_is_older_than(10s, $time)){ print "Is older than 10 seconds<br/>\n"; }
if (time_is_older_than(200m, $time)){ print "Is older than 200 minutes<br/>\n"; }
if (time_is_older_than(2h, $time)){ print "Is older than 2 hours<br/>\n"; }
if (time_is_older_than(4d, $time)){ print "Is older than 4 days<br/>\n"; }
if (time_is_older_than(1y, $time)){ print "Is older than one year<br/>\n"; }