Regex matching in reverse everything after character x

Question

I am struggling to create a regex to match this:

string: this-string-ends-1c25e41b-f5b2-4484-b5b8-7d45ac2dd427

should return: 1c25e41b-f5b2-4484-b5b8-7d45ac2dd427

ie return everything after the 4th "-" character from the end.

I have tried this:

([^-]*$)

But it just matches from the first. Note the first 3 items (this-string-ends) could be any range of values

Answer 1

With preg_replace function:

$s = 'this-string-ends-1c25e41b-f5b2-4484-b5b8-7d45ac2dd427';
$result = preg_replace('/.*?([^-]+(?:-[^-]+){4})$/', '$1', $s);

print_r($result);

The output:

1c25e41b-f5b2-4484-b5b8-7d45ac2dd427

---

Bonus solution with explode , implode and array_slice functions:

$s = 'this-string-ends-1c25e41b-f5b2-4484-b5b8-7d45ac2dd427';
$chunks = explode('-', $s);
$result = (count($chunks) >= 5)? implode('-', array_slice($chunks, -5)) : "";

print_r($result);

The output:

1c25e41b-f5b2-4484-b5b8-7d45ac2dd427

Answer 2

Try the following with preg_match ( DEMO ):

$str = 'this-string-ends-1c25e41b-f5b2-4484-b5b8-7d45ac2dd427';
preg_match('/([^-]+(?:-[^-]+){4})$/', $str, $matches);

var_dump($matches);

Output:

array (size=2)
  0 => string '1c25e41b-f5b2-4484-b5b8-7d45ac2dd427' (length=36)
  1 => string '1c25e41b-f5b2-4484-b5b8-7d45ac2dd427' (length=36)

Regexless Solution: Here is a solution using implode , explode and strrev :

$str = 'this-string-ends-1c25e41b-f5b2-4484-b5b8-7d45ac2dd427';
$str = strrev($str);
$arr = explode('-', $str, 6);
unset($arr[5]);
$imp = implode('-', $arr);
$matched = strrev($imp);

var_dump($matched);

Output:

string '1c25e41b-f5b2-4484-b5b8-7d45ac2dd427' (length=36)

Answer 3

How about:

$string     = 'this-string-ends-1c25e41b-f5b2-4484-b5b8-7d45ac2dd427';
$string = preg_replace('/^.*?-((?:[^-]*-){4}[^-]*)$/', "$1", $string);
echo $string,"\n";

Output:

1c25e41b-f5b2-4484-b5b8-7d45ac2dd427

Answer 4

Use:

[^-]*-[^-]*-[^-]*-[^-]*-[^-]*$

The regex searches for a string which has a string of chars different from '-' ( [^-]* ), followed by - , followed by the same pattern 4 time, then the string ends ( $ )

Testing on: https://regex101.com/r/49fCit/2 ,the output is:

1c25e41b-f5b2-4484-b5b8-7d45lac2dd427

Answer 5

Try this

([0-9a-zA-Z]*-[0-9a-zA-Z]*){4}$

It will take the last 4 hyphen with combination of letters or numbers (or not ) in between

Answer 6

You want to extract a substring of five groups of hexadecimal characters separated by four hyphens at the end of the string. You can do it with preg_match :

if ( preg_match('~(?>[^-]+-?\b){5}$~', $str, $m) )
    echo $m[0];

You can also be more explicit using [[:xdigit:]] in place of [^-] .