php将日期格式转换成xx天前的格式

// convert a date into a string that tells how long ago
// that date was.... eg: 2 days ago, 3 minutes ago.
function ago($d) {
$c = getdate();
$p = array('year', 'mon', 'mday', 'hours', 'minutes', 'seconds');
$display = array('year', 'month', 'day', 'hour', 'minute', 'second');
$factor = array(0, 12, 30, 24, 60, 60);
$d = datetoarr($d);
for ($w = 0; $w < 6; $w++) {
if ($w > 0) {
$c[$p[$w]] += $c[$p[$w-1]] * $factor[$w];
$d[$p[$w]] += $d[$p[$w-1]] * $factor[$w];
}
if ($c[$p[$w]] - $d[$p[$w]] > 1) {
return ($c[$p[$w]] - $d[$p[$w]]).' '.$display[$w].'s ago';
}
}
return '';
}
// you can replace this if need be.
// This converts my dates returned from a mysql date string
// into an array object similar to that returned by getdate().
function datetoarr($d) {
preg_match("/([0-9]{4})(-)([0-9]{2})(-)([0-9]{2})([0-9]{2})(:)([0-9]{2})(:)([0-9]{2})/",$d,$matches);
return array(
'seconds' => $matches[10],
'minutes' => $matches[8],
'hours' => $matches[6],
'mday' => $matches[5],
'mon' => $matches[3],
'year' => $matches[1],
);
}