Why does PHP use the array_combine method to affect the original array?

Please see the code below:

There are two arrays before processing arrTitle and arrHref,

The content of arrTitle is as follows:

arrHrefThe content is as follows:

<code class="php">//将title数组中首元素取出,作为栏目标题
foreach ($arrTitle as &$title) {
    $text [] = $title[0];
    unset($title[0]);
}

//将href数组中首元素取出,作为栏目url
foreach ($arrHref as &$href) {
    $url [] = $href[0];
    unset($href[0]);
}

print_r($arrTitle);
//重新组织title项
$title = array_combine($text, $url);

print_r($arrTitle);die;</code>

Run the above PHP code to extract and remove the first element of each item in title and href. However, the problem arises. Before executing array_combine, $arrTitle looks like this:

However, after executing array_combine, $arrTitlebecomes like this:

Why, the last element of $arrTitle becomes the result of array_combine(), but the array_combine() function does not modify $arrTitle?

Reply content:

Please see the code below:

There are two arrays before processing arrTitle and arrHref,

The content of arrTitle is as follows:

arrHrefThe content is as follows:

<code class="php">//将title数组中首元素取出,作为栏目标题
foreach ($arrTitle as &$title) {
    $text [] = $title[0];
    unset($title[0]);
}

//将href数组中首元素取出,作为栏目url
foreach ($arrHref as &$href) {
    $url [] = $href[0];
    unset($href[0]);
}

print_r($arrTitle);
//重新组织title项
$title = array_combine($text, $url);

print_r($arrTitle);die;</code>

Run the above PHP code to extract and remove the first element of each item in title and href. However, the problem arises. Before executing array_combine, $arrTitle looks like this:

However, after executing array_combine, $arrTitlebecomes like this:

Why, the last element of $arrTitle becomes the result of array_combine(), but the array_combine() function does not modify $arrTitle?

<code>**$title** = array_combine($text, $url);
</code>

$title here has the same name as $title in the loop above, just change the name. There is no block scope in php.

This bug has been resolved. Thanks to @whyreal for pointing out the duplicate name issue.

Since in the foreach loop, the array is traversed in reference mode, when the loop ends, $title points to the last set of elements of $arrTitle.

Since PHP does not have a block-level scope, in $title = array_combine($arr1, $arr2), then the $title also modifies the last group of elements it points to $arrTitle, resulting in a bug.

Modify the name behind $title to eliminate this bug.