Use a variable in preg_grep matching in PHP

Question

How can I use a variable name in preg_grep?

I'm iterating over an array of file names and trying to match to the file name in the format of "Some File-0.png", "Some File-1.png" so on and so forth.

Here's what I'm using.

$arrayRet=preg_grep("/$filename-\\d*.png/",$ret);

I know the $ character is a special pattern character but I don't know how to escape it or if that's even the problem.

I've tried this but to no avail.

$pattern = "/".$filename."-\d*.png/";
$arrayRet=preg_grep($pattern,$ret);

EDIT: $ret returns a list of files such as this.

Array
(
    [0] => C:\inetpub\wwwroot\Presentation\thumbs\...\Client References - Government-0.png
    [1] => C:\inetpub\wwwroot\Presentation\thumbs\...\Client References - Government-1.png
    [2] => C:\inetpub\wwwroot\Presentation\thumbs\...\Client References - National-0.png
    [3] => C:\inetpub\wwwroot\Presentation\thumbs\...\Client References - National-1.png
    [4] => C:\inetpub\wwwroot\Presentation\thumbs\...\Client References - National-2.png
    [5] => C:\inetpub\wwwroot\Presentation\thumbs\...\Client References-0.png
    [6] => C:\inetpub\wwwroot\Presentation\thumbs\...\Client References-1.png
    [7] => C:\inetpub\wwwroot\Presentation\thumbs\...\Company Profile-0.png
    [8] => C:\inetpub\wwwroot\Presentation\thumbs\...\Company Profile-1.png
    [9] => C:\inetpub\wwwroot\Presentation\thumbs\...\Corporate Overview - Short Version-0.png
    [10] => C:\inetpub\wwwroot\Presentation\thumbs\...\Corporate Overview - Short Version-1.png

Note - I've added ellipses to shorten the path.

$filename would be Client References - Government , Client References - National , Client References and so on.

Answer 1

Use preg_quote to escape all special regex meta characters:

$pattern = '/' . preg_quote($filename, '/') . '-\d*.png/';
$arrayRet = preg_grep($pattern, $ret);