array_map/array_filter/array_walk traverses the array in the same way as foreach. Who wants to be faster?-PHP Tutorial-php.cn

array_map/array_filter/array_walk traverses the array in the same way as foreach. Who wants to be faster?

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Release： 2016-10-22 00:14:25

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array_walk is equivalent to foreach:

<code>$arr = ['Client'=>'jQuery','Server'=>'PHP'];
array_walk($arr, function($v, $k) {
    echo "键:$k 值:$v\n";
});</code>

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For example, remove the leading and trailing whitespace of the array $arr element:

<code>array_walk($arr, function(&$v) { $v = trim($v); });
foreach($arr as &$v) { $v = trim($v); }
array_filter: 用回调函数过滤数组中的单元,返回过滤后的数组

var_export(
    array_filter([1, 2, 3], function($v) {
        return $v > 1;
    })
);
和
foreach([1, 2, 3] as $k => $v) {
    if($v > 1) {
        $tmp[$k] = $v;
    }
}
var_export($tmp);
都输出:
array (
  1 => 2,
  2 => 3,
)</code>

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PHP array mapping reduction (MapReduce):

<code>array_map/array_reduce
array_map: 将回调函数作用到给定数组的单元上
var_export(
    array_map(function ($v) {
        return $v * $v;
    }, [1, 2, 3])
);
和
foreach([1, 2, 3] as $v) {
    $tmp[] = $v * $v;
}
var_export($tmp);
都输出:
array (
  0 => 1,
  1 => 4,
  2 => 9,
)</code>

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array_reduce: Use the callback function to iteratively reduce the array into a single value
//Output 16, which is 10+1+2+3, with 10 as the initial value.

<code>echo array_reduce([1, 2, 3], function($result, $item) {
    $result = $result + $item;
    return $result;
}, 10);
用foreach表达:
$result = 10;
foreach([1, 2, 3] as $v) {
    $result = $result + $v;
}
echo $result;</code>

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The execution effects are the same, but is it faster to use functions or foreach?

Reply content:

array_walk is equivalent to foreach:

<code>$arr = ['Client'=>'jQuery','Server'=>'PHP'];
array_walk($arr, function($v, $k) {
    echo "键:$k 值:$v\n";
});</code>

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For example, remove the leading and trailing whitespace of the array $arr element:

<code>array_walk($arr, function(&$v) { $v = trim($v); });
foreach($arr as &$v) { $v = trim($v); }
array_filter: 用回调函数过滤数组中的单元,返回过滤后的数组

var_export(
    array_filter([1, 2, 3], function($v) {
        return $v > 1;
    })
);
和
foreach([1, 2, 3] as $k => $v) {
    if($v > 1) {
        $tmp[$k] = $v;
    }
}
var_export($tmp);
都输出:
array (
  1 => 2,
  2 => 3,
)</code>

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PHP array mapping reduction (MapReduce):

<code>array_map/array_reduce
array_map: 将回调函数作用到给定数组的单元上
var_export(
    array_map(function ($v) {
        return $v * $v;
    }, [1, 2, 3])
);
和
foreach([1, 2, 3] as $v) {
    $tmp[] = $v * $v;
}
var_export($tmp);
都输出:
array (
  0 => 1,
  1 => 4,
  2 => 9,
)</code>

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array_reduce: Use the callback function to iteratively reduce the array into a single value

//Output 16, which is 10+1+2+3, with 10 as the initial value.

<code>echo array_reduce([1, 2, 3], function($result, $item) {
    $result = $result + $item;
    return $result;
}, 10);
用foreach表达:
$result = 10;
foreach([1, 2, 3] as $v) {
    $result = $result + $v;
}
echo $result;</code>

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The execution effects are the same, but is it faster to use functions or foreach?