Quick Question PHP - Strip String Pattern

You can find the position of the last underscore with this:
http://php.net/manual/en/function.strrpos.php

You can get the substring from that position to the end of the string with this:
http://php.net/manual/en/function.substr.php

I'll set up a test for you and show you the code.

<?php // demo/temp_iceman19330.php
/**
 * http://www.experts-exchange.com/questions/28926349/Quick-Question-PHP-Strip-String-Pattern.html
 */
error_reporting(E_ALL);
echo '<pre>';

$delimiter = '_';

$testcases = array
( 'XCTY_MMYT_2222-1110-XX'
, 'ACDS_FFFFFFF-14XX-122121'
)
;
foreach ($testcases as $str)
{
    $dlm = strrpos($str, $delimiter) + 1;
    $new = substr($str, $dlm);

    echo PHP_EOL;
    echo $str;
    echo ' RESULT: ';
    echo $new;
}

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Lemme know if you have any questions!

@Ray: I think in this case a regex solution is better.

Reasons:
1. very easy to understand string: ".*_" means "everything up to the last _"
2. it can be used for multi line input strings in one go, without changing anything:

$subject = "XCTY_MMYT_2222-1110-XX";
$result = preg_replace('/.*_/', '', $subject);
echo $result;

$subject = "XCTY_MMYT_2222-1110-XX
            ACDS_FFFFFFF-14XX-122121
            ABC_111-111-111";
$result = preg_replace('/.*_/', '', $subject);
echo $result;

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My normal two cents would say that the str_ functions will always be faster than preg_, but strrpos is a slow beast (relatively-speaking), so it will run slower than preg_ in most scenarios.

Either way is lightning-quick, although the fastest way is in Dan's last post where he has all the values in one string and runs one preg_replace() call against it (virtually eliminating the overhead that comes from all the repeated function calls). So if the OP is looking to do this repeatedly on a massive scale (e.g. millions of entries), then his best bet is to read them all in as one string and do the single preg_replace on it. It'll be a couple seconds faster than the alternatives.

Probably none of this is actually relevant to the OP, but interesting info nonetheless (stupid strrpos!). :)

https://www.experts-exchange.com/articles/7830/A-Quick-Tour-of-Test-Driven-Development.html

The only reason I used an array was to facilitate testing.  My guess was that this data comes from some external source - a database, an API, a scanner, a form input - something like that, and that the inputs were arriving one-at-a-time.  If the number of transformations is less than several hundred per second, it may be hard to find much value in optimization.  Nothing against optimization, but one hour of debugging == a lot of computer cycles, and sometimes the lazy-easy code is a good way to go.  Premature optimization is usually considered an anti-practice.

(From random thoughts) has anybody tried benchmarking strrpos() against strrev() + strpos()?  It would be especially interesting to see the difference in a high-performance environment with PHP 7 or HHVM.

This worked really well on both the single and double underscore.
Thanks

You're welcome.

Glad I could help!