我這段代碼輸出$key后會多一個s,不知道是怎么出來的，望大家可以解答一下

<?php
?$students?=?array(
'2010'=>array('令狐沖',"59","f"),
'2011'=>array('林平之',"44","f"),
'2012'=>array('曲洋',"89","m"),
'2013'=>array('任盈盈',"92","m"),
'2014'=>array('向問天',"93","f"),
'2015'=>array('任我行',"87","m"),
'2016'=>array('沖虛',"58","f"),
'2017'=>array('方正',"74","d"),
'2018'=>array('岳不群',"91","e"),
'2019'=>array('寧中則',"90","s"),
);//10個學生的學號、姓名、分數(shù)，用數(shù)組存儲
?
foreach($students?as?$key?=>?$val)
{?//使用循環(huán)結(jié)構(gòu)遍歷數(shù)組,獲取學號?
?????echo?$key;?//輸出學號
	?echo?":";
	?//循環(huán)輸出姓名和分數(shù)
	?foreach($val?as?$v)
	{
		//echo?$v;?
	?}
	?echo?"<br?/>";
}

{
????echo?$v."<br?/>";
}
?>

晴曉剘

2017-02-20

源自：PHP入門篇 6-15

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dog_493310 回答被采納 +3 積分
2017-02-20

<?php
$students?=?array(
???'2010'=>array('令狐沖',"59","f"),
???'2011'=>array('林平之',"44","f"),
???'2012'=>array('曲洋',"89","m"),
???'2013'=>array('任盈盈',"92","m"),
???'2014'=>array('向問天',"93","f"),
???'2015'=>array('任我行',"87","m"),
???'2016'=>array('沖虛',"58","f"),
???'2017'=>array('方正',"74","d"),
???'2018'=>array('岳不群',"91","e"),
???'2019'=>array('寧中則',"90","s"),
);//10個學生的學號、姓名、分數(shù)，用數(shù)組存儲
$a=1;?//計數(shù)器
foreach($students?as?$key?=>?$val){?//使用循環(huán)結(jié)構(gòu)遍歷數(shù)組,獲取學號
//????????????echo?$key;?//輸出學號
//????????????echo?":";
???????????//循環(huán)輸出姓名和分數(shù)
???????????foreach($val?as?$v){
???????????????????echo?"<br?/>";
???????????????????echo?"第".$a++.'次?$v的值為'.":".$v;
???????????}
???????????echo?"<br?/>";
???????}

{
???echo?$v."<br?/>";???//當最后遍歷完畢后，$V的值為s?
}

echo?var_dump($v);??//string?'s'?(length=1)
?>

其實不難理解，我們把每一次遍歷時，把 $v 這個變量打印出來看一下就明白了。

當最后一次遍歷后，變量$v 所存放的值為 ‘s’