如何在PHP中修剪数组中的空格

I'm trying to parse a CSV file and as part of it I would like to remove leading/trailing whitespace from all of my cells. Since it's a CSV file it's formatted like a 2D array. Initially I tried:

foreach($csv as $row){
    foreach($row as $cell){
        $cell = trim($cell);
    }
}

However the result was untrimmed.

Next I tried using array_map as suggested here.

$csv = array_map('trim', $csv);

This gave me back an array of empty rows. So I also tried

foreach($csv as $row){
    $row = array_map('trim', $row);
}

Which like my first attempt didn't change anything.

Here's the CSV data I'm using as my input:

First Name,Last Name,Contact Method,Phone, Email John,Doe,Email,1-XXX-XXX-XXXX, john@example.com Jane,Doe,Phone Call,1-XXX-XXX-XXXX,jane@example.com

In particular I was trying to get my script to trim the leading space in the last cell of the first row (" Email" => "Email").

You are not modifying the original array when you do the trim. You should get the values by reference in the foreach loop.

foreach($csv as &$row){
    foreach($row as &$cell){
        $cell = trim($cell);
    }
}

From the documentation:

In order to be able to directly modify array elements within the loop precede $value with &. In that case the value will be assigned by reference.

If you are seeing it like you put here,

" Email" => "Email"

you'll have to trim it from the key, can you show how you are assigning the named headers. Because I would trim it there, but using array_map('trim', $data) will remove the whitespace, I do that all day long.

Well to just clean the keys you can do,

 $keys = array_map( 'trim', array_keys($data) );
 $data = array_combine( $keys, $data );

You need to reference $row in order to make changes to the array (note the &):

foreach($csv as &$row){
    $row = array_map('trim', $row);
}

$input = [
    'parent' => [
        'child' => ' element to be trimmed '
    ]
];
array_walk_recursive($input, function (&$item) {
    if (!is_array($item)) {
        $item = trim($item);
    }
});