php实现的DateDiff和DateAdd时间函数代码分享

扩展php中的时间函数DateDiff和DateAdd

    function DateDiff($part, $begin, $end)
    {
    $diff = strtotime($end) - strtotime($begin);
    switch($part)
    {
    case "y": $retval = bcdiv($diff, (60 * 60 * 24 * 365)); break;
    case "m": $retval = bcdiv($diff, (60 * 60 * 24 * 30)); break;
    case "w": $retval = bcdiv($diff, (60 * 60 * 24 * 7)); break;
    case "d": $retval = bcdiv($diff, (60 * 60 * 24)); break;
    case "h": $retval = bcdiv($diff, (60 * 60)); break;
    case "n": $retval = bcdiv($diff, 60); break;
    case "s": $retval = $diff; break;
    }
    return $retval;
    }

    function DateAdd($part, $number, $date)
    {
    $date_array = getdate(strtotime($date));
    $hor = $date_array["hours"];
    $min = $date_array["minutes"];
    $sec = $date_array["seconds"];
    $mon = $date_array["mon"];
    $day = $date_array["mday"];
    $yar = $date_array["year"];
    switch($part)
    {
    case "y": $yar += $number; break;
    case "q": $mon += ($number * 3); break;
    case "m": $mon += $number; break;
    case "w": $day += ($number * 7); break;
    case "d": $day += $number; break;
    case "h": $hor += $number; break;
    case "n": $min += $number; break;
    case "s": $sec += $number; break;
    }
    return date("Y-m-d H:i:s", mktime($hor, $min, $sec, $mon, $day, $yar));
    }

    Function DateAdd($part, $n, $date)
    {
    switch($part)
    {
    case "y": $val = date("Y-m-d H:i:s", strtotime($date ." +$n year")); break;
    case "m": $val = date("Y-m-d H:i:s", strtotime($date ." +$n month")); break;
    case "w": $val = date("Y-m-d H:i:s", strtotime($date ." +$n week")); break;
    case "d": $val = date("Y-m-d H:i:s", strtotime($date ." +$n day")); break;
    case "h": $val = date("Y-m-d H:i:s", strtotime($date ." +$n hour")); break;
    case "n": $val = date("Y-m-d H:i:s", strtotime($date ." +$n minute")); break;
    case "s": $val = date("Y-m-d H:i:s", strtotime($date ." +$n second")); break;
    }
    return $val;
    }