Which foreach method is better for processing list data in PHP?-PHP Tutorial-php.cn

Which foreach method is better for processing list data in PHP?

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Release： 2016-07-06 13:52:59

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In development, it is often necessary to process list data taken from the database,

There are three writing methods I have seen below, all of which can get the same result. I am always accustomed to using the first one.

Which one is better in terms of readability and performance?

List data such as:

<code>$list = [
    [
        'uid'=>100,
        'username'=>'test100',
        'nickname'=>'php_1',
        'gender'=>1,
    ],
    [
        'uid'=>200,
        'username'=>'test200',
        'nickname'=>'php_2',
        'gender'=>2,
    ],
    [
        'uid'=>300,
        'username'=>'test300',
        'nickname'=>'php_3',
        'gender'=>0,
    ],
];</code>

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Writing method 1, modify in the original array:

<code>foreach($list as $k=>$v){
    if($v['gender']==0){
        $list[$k]['gender']='妖人';
    }else{
        $list[$k]['gender']='人';
    }
}</code>

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Writing method 2, modify the original array, use reference:

<code>foreach($list as &$v){
    if($v['gender']==0){
       $v['gender']='妖人';
    }else{
       $v['gender']='人';
    }
}</code>

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Writing 3, define a new array:

<code>
$data = [];
foreach($list as $k=>$v){
    if($v['gender']==0){
        $v['gender']='妖人';
    }else{
        $v['gender']='人';
    }
    $data[] = $v;
}</code>

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Reply content:

In development, it is often necessary to process list data taken from the database,

There are three writing methods I have seen below, all of which can get the same result. I am always accustomed to using the first one.

Which one is better in terms of readability and performance?

List data such as:

<code>$list = [
    [
        'uid'=>100,
        'username'=>'test100',
        'nickname'=>'php_1',
        'gender'=>1,
    ],
    [
        'uid'=>200,
        'username'=>'test200',
        'nickname'=>'php_2',
        'gender'=>2,
    ],
    [
        'uid'=>300,
        'username'=>'test300',
        'nickname'=>'php_3',
        'gender'=>0,
    ],
];</code>

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Writing method 1, modify in the original array:

<code>foreach($list as $k=>$v){
    if($v['gender']==0){
        $list[$k]['gender']='妖人';
    }else{
        $list[$k]['gender']='人';
    }
}</code>

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Writing method 2, modify the original array, use reference:

<code>foreach($list as &$v){
    if($v['gender']==0){
       $v['gender']='妖人';
    }else{
       $v['gender']='人';
    }
}</code>

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Writing 3, define a new array:

<code>
$data = [];
foreach($list as $k=>$v){
    if($v['gender']==0){
        $v['gender']='妖人';
    }else{
        $v['gender']='人';
    }
    $data[] = $v;
}</code>

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Use 1 more often
Although 2 is the simplest way to write, there are pitfalls in quoting under foreach
If you use the $v variable again outside of foreach, the last value of foreach may be changed. , of course it can be guaranteed that this problem will not occur if it is not used

array_map

I generally use the first way of writing
The second way of writing is prone to problems

The recommended way to quote is writing method 2

The second method is better. You have already foreached it. There is already a one-dimensional array, so why do you need to fetch it from the list?

select if(gender=0,'魔人','人') as gendername ……

Get used to the first method