PHP Regex with recursively filter string and append sub-string to array

Question

I'm basically trying to extract parts of a string AFTER a character "/" but using PHP PCRE (Regular Expressions) NOT PHP substr() function, I would like to test if the initial string has multiple "/" characters using a combination of PHP PCRE (Regular Expressions) and preg_match() or preg_match_all().

I am able to select for a SINGLE iteration using a regular expression.

<?php
  $rules = array(
    'dbl'     => "/(?'d'[^/]+)/(?'p'[^/]+)", // '.../a/a' DOUBLE ITERATION
    'single'     => "/(?'d'[\w\-]+)",// '.../a' SINGLE ITERATION
    'multiple'     => "" //MULTIPLE ITERATION
  );
  $string = "a/b/c/d/e";
  foreach ( $rules as $action => $rule ) {
    if ( preg_match_all( '~^'.$rule.'$~i', $string, $params ) ) {
      switch ($action) {
        case 'multiple':
          $arr = explode("/", $string);
          print_r($arr);
          //do something
        ...
      }
    }
  }


?>

I know this is because of my lack of sufficient knowledge of Regular Expressions, however, I need a dynamic Regex code to match the condition that the initial string has multiple "/" characters and then recursively store these substrings to an array.

Something like if(preg_match('~^[^/]+(?:/[^/]+)+/?$~', $string)) { print_r(explode('/', $string)); }? If you want to check for at least 2 /s, replace the last + with {2,} — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jul 24, 2019 at 12:12
I would approach this differently: I would first explode $string on / and then apply logic based on the number of elements in the results. — joanis
– joanis, Commented Jul 24, 2019 at 12:25
Hi @WiktorStribiżew, Yes, thats exactly what i needed. Kindly post your answer so that i may accept it. — Quatban Taco
– Quatban Taco, Commented Jul 24, 2019 at 12:28
I just wanted to make sure I understand the final result. @joanis idea is better, you do not actually need a regex here. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jul 24, 2019 at 12:33

joanis · Accepted Answer · 2019-07-24 12:39:13Z

0

I would approach this differently: I would first explode $string on / and then apply logic based on the number of elements in the results.

<?php
  $string = "a/b/c/d/e";
  $arr = explode("/", $string);
  if (count($arr) > 2) {
    print_r($arr);
    // do something knowing there were 2 or more slashes in $string
  }
?>

If you need different actions for 0, 1 or 2 slashes, add elseif blocks testing for fewer elements in $arr and put the corresponding actions there.

answered Jul 24, 2019 at 12:39

joanis

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2 Comments

Quatban Taco Over a year ago

This works but the aim was using Regexes to handle this as stated in the question.

joanis Over a year ago

Now I am curious, what is your use case for absolutely needing to solve this with a regex?

Quatban Taco · Accepted Answer · 2019-07-27 11:50:47Z

0

To answer the question, Using Wiktor Stribiżew's Regex Code:

<?php
  $rules = array(
    'dbl'     => "/(?'d'[^/]+)/(?'p'[^/]+)", // '.../a/a' DOUBLE ITERATION
    'single'     => "/(?'d'[\w\-]+)",// '.../a' SINGLE ITERATION
    'multiple'     => "/[^/]+(?:/[^/]+){2,}/?" //MULTIPLE ITERATION
  );
  $string = "a/b/c/d/e";
  foreach ( $rules as $action => $rule ) {
    if ( preg_match_all( '~^'.$rule.'$~i', $string, $params ) ) {
      switch ($action) {
        case 'multiple':
          $arr = explode("/", $string);
          print_r($arr);
          //do something
        ...
      }
    }
  }


?>

For others who reference this resource, kindly upvote Wiktor Stribiżew's answer once/ if he posts it.

answered Jul 27, 2019 at 11:50

Quatban Taco

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