array_walk vs array_map vs foreach

Question

我试图比较这三个,但它似乎只有array_map作用.

$input = array( '  hello   ','whsdf                                    ','                              lve you','                              ');
$input2 = array( '  hello   ','whsdf                                    ','                              lve you','                              ');
$input3 = array( '  hello   ','whsdf                                    ','                              lve you','                              ');

$time_start = microtime(true);
$input = array_map('trim',$input);
$time_end = microtime(true);
$time = $time_end - $time_start;

echo "Did array_map in $time seconds<br>";

foreach($input as $in){
    echo "'$in': ".strlen($in)."<br>";
}

////////////////////////////////////////////////

$time_start = microtime(true);
array_walk($input2,'trim');
$time_end = microtime(true);
$time = $time_end - $time_start;

echo "Did array_walk in $time seconds<br>";

foreach($input2 as $in){
    echo "'$in': ".strlen($in)."<br>";
}

////////////////////////////////////////////////


$time_start = microtime(true);
foreach($input3 as $in){
    $in = trim($in);
}
$time_end = microtime(true);
$time = $time_end - $time_start;

echo "Did foreach in $time seconds<br>";

foreach($input3 as $in){
    echo "'$in': ".strlen($in)."<br>";
}

我究竟做错了什么？这是输出:

Did array_map in 0.00018000602722168 seconds
'hello': 5
'whsdf': 5
'lve you': 7
'': 0
Did array_walk in 0.00014209747314453 seconds
' hello ': 10
'whsdf ': 41
' lve you': 37
' ': 30
Did foreach in 0.00012993812561035 seconds
' hello ': 10
'whsdf ': 41
' lve you': 37
' ': 30

它不是修剪array_walk和foreach循环.

Answer 1

array_walk不看结果函数给出的结果.相反,它传递回调对项目值的引用.所以你的代码需要它

function walk_trim(&$value) {
    $value = trim($value);
}

foreach也不会存储更改的值.将其更改为

foreach ($input3 as &$in) {
    $in = trim($in);
}

了解更多关于引用.

Answer 2

从PHP 5.3开始可以使用匿名函数。前任：

$arr = array('1<br/>','<a href="#">2</a>','<p>3</p>','<span>4</span>','<div>5</div>');
array_walk($arr, function(&$arg){
    $arg = strip_tags($arg);
});
var_dump($arr); // 1,2,3,4,5 ;-)

玩得开心。