php 中常用的日期处理函数

// date_format2($rs['time'],'%y年%m月%d日%h时%m分%s秒');
function date_format2($string, $format='%b %e, %y', $default_date=null)
{
    if (substr(php教程_os,0,3) == 'win') {
           $_win_from = array ('%e',  '%t',       '%d');
           $_win_to   = array ('%#d', '%h:%m:%s', '%m/%d/%y');
           $format = str_replace($_win_from, $_win_to, $format);
    }
    if($string != '') {
        return strftime($format, smarty_make_timestamp($string));
    } elseif (isset($default_date) && $default_date != '') {
        return strftime($format, smarty_make_timestamp($default_date));
    } else {
        return;
    }
}
function smarty_make_timestamp($string){
    if(empty($string)) {
        $string = "now";
    }
    $time = strtotime($string);
    if (is_numeric($time) && $time != -1)
        return $time;
    if (preg_match('/^d{14}$/', $string)) {
        $time = mktime(substr($string,8,2),substr($string,10,2),substr($string,12,2),
               substr($string,4,2),substr($string,6,2),substr($string,0,4));

        return $time;
    }
    $time = (int) $string;
    if ($time > 0)
        return $time;
    else
        return time();
}