正则表达式为PHP数组的每个项添加一个后缀

I have a PHP array of strings, which I would like to postfix with a character. below regular expression to add something prefix of each array elements:

$prefixed_array = preg_filter('/^/', 'prefix_', $array);

But, I need add postfix.

Essentially I would like to go from this:

$array = ["a", "b", "c", "d", "f"];

To this:

$array = ["a_M", "b_M", "c_M", "d_M", "f_M"];

I can do it with foreach, but need a regular expresion (Just Regex).

If you want to use preg_filter with a regex for this, replace ^ with $ (the end of string) (or \z - the very end of the string):

$array = ["a", "b", "c", "d", "f"];
$suffixed_array = preg_filter('/$/', '_M', $array);
print_r($suffixed_array);

See the PHP demo

A non-regex way is to use array_map like this:

$suffixed_array = array_map(function ($s) {return $s . '_M';}, $array);

See this PHP demo.

additional approach using array_map

$array = ["a", "b", "c", "d", "f"];

$array = array_map(function($k) {
    return $k . '_M';
}, $array);

print_r($array);