Some commonly used date array sorting in PHP

function yearArray(){
    $tody = getdate();
    $todyYear = $tody['year'];
    $startYear = 1900-1;
    $i = 1;
    for($startYear; $startYear < $todyYear; $startYear++){
        $yearArr[$i] = $startYear+1;
        $i++;
    }
    return $yearArr;
}

function monthArray(){
    $monthArr = array(1,2,3,4,5,6,7,8,9,10,11,12);
    return $monthArr;
}

function dayArray(){
    $dayArr = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31);
    return $dayArr;
}

function weekArr(){
    return  array('1'=>'星期一','2'=>'星期二','3'=>'星期三','4'=>'星期四','5'=>'星期五','6'=>'星期六','7'=>'星期日');