php - foreach中直接修改数组元素导致value覆盖下一个元素

Question

我的简单循环采用坐标和地名列表，例如:

(59.436961) (24.753575) (Revel, Estonia) (Born)
(-34.847745) (138.507362) (Port Adelaide) (Disembarked)
(-33.177085) (138.010057) (Port Pirie) (Residence before enlistment)

它preg_split将它们放入数组 $coords 中，效果很好。然后我在 foreach 循环中遍历它们。我的问题是为什么这样做:

foreach ($coords as &$marker){
    $marker = preg_split('/\\) \\(|\\(|\\)/', $marker, -1, PREG_SPLIT_NO_EMPTY);
}
print_r($coords);

结果:

Array
(
    [0] => Array
        (
            [0] => 59.436961
            [1] => 24.753575
            [2] => Revel, Estonia
            [3] => Born
        )

    [1] => Array
        (
            [0] => -34.847745
            [1] => 138.507362
            [2] => Port Adelaide
            [3] => Disembarked
        )

    [2] => Array
        (
            [0] => -34.847745
            [1] => 138.507362
            [2] => Port Adelaide
            [3] => Disembarked
        )

)

(请注意，元素 [1] 和 [2] 是相同的)- 但是:

foreach ($coords as $marker){
    $marker_array[] = preg_split('/\\) \\(|\\(|\\)/', $marker, -1, PREG_SPLIT_NO_EMPTY);
}
print_r($marker_array);

结果:

Array
(
    [0] => Array
        (
            [0] => 59.436961
            [1] => 24.753575
            [2] => Revel, Estonia
            [3] => Born
        )

    [1] => Array
        (
            [0] => -34.847745
            [1] => 138.507362
            [2] => Port Adelaide
            [3] => Disembarked
        )

    [2] => Array
        (
            [0] => -33.177085
            [1] => 138.010057
            [2] => Port Pirie
            [3] => Residence before enlistment
        )

)

当我尝试直接在循环中修改元素时，是否有我做错或不知道的地方？

Answer 1

在 PHP 5.6 中，我没有看到所描述的行为。你如何解析原始列表？

当我运行时:

<?php

$coords = array('(59.436961) (24.753575) (Revel, Estonia) (Born)',
    '(-34.847745) (138.507362) (Port Adelaide) (Disembarked)',
    '(-33.177085) (138.010057) (Port Pirie) (Residence before enlistment)');

foreach ($coords as &$marker){
    $marker = preg_split('/\\) \\(|\\(|\\)/', $marker, -1, PREG_SPLIT_NO_EMPTY);
}
print_r($d);

它给了我这个:

Array
(
    [0] => Array
        (
            [0] => 59.436961
            [1] => 24.753575
            [2] => Revel, Estonia
            [3] => Born
        )

    [1] => Array
        (
            [0] => -34.847745
            [1] => 138.507362
            [2] => Port Adelaide
            [3] => Disembarked
        )

    [2] => Array
        (
            [0] => -33.177085
            [1] => 138.010057
            [2] => Port Pirie
            [3] => Residence before enlistment
        )

)

但我不推荐使用这种疯狂的结构!

如果你从文本中解析它，那么只需使用 preg_match_all 和类似这样的模式:

'~\(()\)\s*\(()\)\s*\(()\)\s*\(()\)~mu'

即使您有数组中的数据，我也强烈建议您使用 preg_match 进行可预测的数据匹配，而不是为此目的使用 preg_split。但是没有人在第一天就成为大师......