PHP判斷是否已成年

判斷是否成年：
1.判斷年份是否滿18年
2.年份剛好滿18年判斷月份是否大於當前月份；
3.月份相同判斷日期是否大於當前日期

function isAdult(){
	$birth_year = 1999;
	$birth_month = 12;
	$birth_day = 25;
	$today_year = 2019;
	$today_month = 09;
	$today_day = 04;
	$adult = 1;//已成年
	if($birth_year + 18 <= $today_year ){
		if($birth_year + 18 == $today_year ){
			if($birth_month  <= $today_month )
				if($birth_month == $today_month ) $adult = $birth_day > $today_day ? 0 : 1;			
			else
				$adult = 0;
		}
	}else{
		$adult = 0;
	}
	return $adult == 0 ? FALSE : TRUE;
}

其他業務代碼略

//打完收工w(ﾟДﾟ)w