Question

I am running into an issue with preg_replace as I am not well-versed with regular expressions.

I am using this tool to test but the replace isn’t working as expected.

I have this input: http://example.com/test-menu/d/C101.
I am expecting this output: http://example.com/test-menu/d/101. I simply want to remove the letter C.

(the d can be any alphanumeric character)

I am attempting to use this regex.

Here is the php that the site is generating:

<?php 
    $ptn = "/\/test-menu\/(.)\/C/";
    $str = "http://example.com/test-menu/d/C101";
    $rpltxt = "/test-menu/$1";
    echo preg_replace($ptn, $rpltxt, $str);
?>

I am not getting a match with my regular expression. What am I missing here?

Answer 1

Either:

$ptn = '/(?<=\/test-menu\/.\/)C/';
$rpltext = '';

(which uses a positive lookbehind with (?<= ... ))

Or:

$ptn = '/(\/test-menu\/.\/)C/';
$rpltext = '$1';

(which captures the whole preceding string in the first submatch, all except the C)