php array_walk 与 array_map 与 foreach
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/10458660/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
array_walk vs array_map vs foreach
提问by Jürgen Paul
I'm trying to compare these three but it seems only array_mapworks.
我试图比较这三个，但它似乎只array_map有效。
$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($in)."<br>";
}
What Am I Doing Wrong? Here's the output:
我究竟做错了什么？这是输出：
Did array_map in 0.00018000602722168 seconds
'hello': 5
'whsdf': 5
'lve you': 7
'': 0
Did array_walk in 0.00014209747314453 seconds
' hello ': 10
'whsdf ': 41
' lve you': 37
' ': 30
Did foreach in 0.00012993812561035 seconds
' hello ': 10
'whsdf ': 41
' lve you': 37
' ': 30
It's not trimming for array_walkand the foreachloop.
它不是修剪 forarray_walk和foreach循环。
采纳答案by Slava
array_walkdoesn't look at what result function gives. Instead it passes callback a reference to item value. So your code for it to work needs to be
array_walk不看结果函数给出什么。相反，它传递回调对项目值的引用。所以你的代码需要工作
function walk_trim(&$value) {
$value = trim($value);
}
foreachdoesn't store changed values itself either. Change it to
foreach也不存储更改的值本身。将其更改为
foreach ($input3 as &$in) {
$in = trim($in);
}
回答by Valentin Rusk
As of PHP 5.3Anonymous Functions possible. ex:
从PHP 5.3 开始，匿名函数成为可能。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 ;-)
Have fun.
玩得开心。
