日期相减及生成连续日期

一、日期相减：求相差年数、月数、日数

/**
 * 日期相减：相差年数、月数、日数
 *
 * @param $sDate date <p>起始日期</p>
 * @param $eDate date <p>截止日期</p>
 * @param $sign string <p>年:y 月:m 日:d</p>
 *
 * @return int 相差数
 */
function dateSubtraction($sDate, $eDate, $sign = "m")
{
    $z = 0;

    if ($sDate > $eDate) { $temp = $sDate; $sDate = $eDate; $eDate = $temp; }

    $sDate_stamp = strtotime($sDate);
    $eDate_stamp = strtotime($eDate);
    list($date_1['y'], $date_1['m'], $date_1['d']) = explode("-", date('Y-m-d', $sDate_stamp));
    list($date_2['y'], $date_2['m'], $date_2['d']) = explode("-", date('Y-m-d', $eDate_stamp));

    switch ($sign) {
        case "y":
            $z = abs($date_1['y'] - $date_2['y']);
            break;
        case "m":
            $z = abs($date_1['y'] - $date_2['y']) * 12 + $date_2['m'] - $date_1['m'];
            break;
        case "d":
            $z = abs(($sDate_stamp - $eDate_stamp) / 86400);
            break;
    }

    return $z;
}

二、自动生成连续日期：按年度、月度、日

/**
 * 自动生成连续日期：按年度、月度、日
 *
 * @param $sDate date <p>起始日期</p>
 * @param $eDate date <p>截止日期</p>
 * @param $sign string <p>年:y 月:m 日:d</p>
 *
 * @return array 连续日期
 */
function dateContinuous($sDate, $eDate, $sign = "m")
{
    $arrDate = Array();

    if ($sDate > $eDate) { $temp = $sDate; $sDate = $eDate; $eDate = $temp; }

    $n = dateSubtraction($sDate, $eDate, $sign);

    switch ($sign) {
        case "y":
            for ($i = 0; $i <= $n; $i++) {
                $arrDate[] = date("Y-m-d", strtotime("+" . $i . " years", strtotime($sDate)));
            }
            break;
        case "m":
            for ($i = 0; $i <= $n; $i++) {
                $arrDate[] = date("Y-m-d", strtotime("+" . $i . " months", strtotime($sDate)));
            }
            break;
        case "d":
            for ($i = 0; $i <= $n; $i++) {
                $arrDate[] = date("Y-m-d", strtotime("+" . $i . " days", strtotime($sDate)));
            }
            break;
    }

    return $arrDate;
}