//根据生日计算年龄
function birToAge($birthday){
    if(!empty($birthday)){
        $age = null;
        $year = date('Y',strtotime($birthday));
        $month = date('m',strtotime($birthday));
        $now_year = date('Y');
        $now_month = date('m');
        $yearDiff = $now_year-$year;
        $monthDiff = $now_month-$month;
        if($yearDiff==0){
            if($monthDiff==0){
                $age = "未满月";
            }else{
                $age = $monthDiff."个月";
            }
        }else if($yearDiff<0){
            $age = "生日格式不对";
        }else{
            if($monthDiff==0){
                $age = $yearDiff."岁";
            }else if($monthDiff<0){
                $ageYer = $yearDiff-1;
                if($ageYer==0){
                    $age = 12-$month+$now_month."月";
                }else{
                    $age = ($yearDiff-1)."岁".(12-$month+$now_month)."月";
                }
            }else{
                $age = $yearDiff."岁".$monthDiff."月";
            }
        }
        return $age;
    }
}