CODEWITHSUNDEEP
phpregexstring
Dan Hastings
Dan Hastings

Reputation: 3280

Dynamically Replace Substring With Substring Using PHP

I have a body of text stored as a string. There are multiple substrings that i want to replace with a substring of that substring. This is a typical substring that i want to replace (note there are multiple substrings i want to replace). 

$String = "loads of text [[gibberish text|Text i Want]] more text  [[gibberish text|Text i Want]] more text [[if no separator then  just remove tags]]";

$String = deleteStringBetweenStrings("[[", "|", $String , true);

deleteStringBetweenStrings is a recursive function that will delete all code between the 2 substrings (including the substrings) this will do what i want for the first substring but goes a bit crazy after this.

function deleteStringBetweenStrings($beginning, $end, $string, $recursive)
{
    $beginningPos = strpos($string, $beginning);
    $endPos = strpos($string, $end);

if ($beginningPos === false || $endPos === false) 
{
    return $string;
}

$textToDelete = substr($string, $beginningPos, ($endPos + strlen($end)) - $beginningPos);

$string = str_replace($textToDelete, '', $string);

if (strpos($string, $beginning) && strpos($string, $end) && $recursive == true) 
{
    $string = deleteStringBetweenStrings($beginning, $end, $string, $recursive);
}
return $string;
}

Is there a more efficient way for me to do this?

Expected output = "loads of text Text i Want more text Text i Want more text if no separator then just remove tags"

Upvotes: 1

Views: 272

Answers (3)

Avinash Raj
Avinash Raj

Reputation: 174706

Regex and regex only....

Just use the below regex to match the text which you don't want and then replace it with an empty string.

(?<=\[\[)(?:(?!\]]|\|).)*\||\[\[|\]\]

DEMO

Code:

<?php
$str = "loads of text [[gibberish text|Text i Want]] more text [[gibberish text|Text i Want]] more text [[if no separator then just remove tags]]";
echo preg_replace("/(?<=\[\[)(?:(?!\]]|\|).)*\||\[\[|\]\]/m", "", $str);
?>

Output:

loads of text Text i Want more text Text i Want more text if no separator then just remove tags

How i figure it out?

  • (?<=\[\[) Looks after to [[ symbols.
  • (?:(?!\]]|\|).)* Match any character but not of ]] or | symbol zero or more times.
  • \| A literal | symbol. This ensures that the match must contain a | symbol before it reaches the closing parenthesis ]]
  • So the regex i explained previously would match gibberish text| only in this [[gibberish text|Text i Want]] type of string and it won't touch this [[if no separator then just remove tags]]
  • | OR
  • \[\[ Now match [[
  • | OR
  • \]\] Symbols. Removing all the matched characters will give you the desired output.

Upvotes: 1

RichardBernards
RichardBernards

Reputation: 3097

Something like this should do the trick (whilst preserving the ability to add your own start and end strings):

function deleteStringBetweenStrings($start, $end, $string) {
    // create a pattern from the input and make it safe to use in a regular expression
    $pattern = '|' . preg_quote($start) . '(.*)' . preg_quote($end) . '|U';
    // replace every occurrence of this pattern with an empty string in full $string
    return preg_replace($pattern, '', $string);
}


$String = "loads of text [[gibberish text|Text i Want]] more text  [[gibberish text|Text i Want]] more text [[if no separator then  just remove tags]]";

$String = deleteStringBetweenStrings("[[", "|", $String);

Upvotes: 1

motanelu
motanelu

Reputation: 4025

Try this one:

$string = 'loads of text [[gibberish text|Text i Want]] more text  [[gibberish text|Text i Want]] more text [[if no separator then  just remove tags]]';

function doReplace($matches) {
    $str = $matches[2];
    if (strpos($str, '|')) {
        $parts = explode('|', $str);
        return $parts[1];
    } else {
        return $str;
    }
}
echo preg_replace_callback('/(\[\[(.*?)\]\])/', 'doReplace', $string);

It echoes 

loads of text Text i Want more text Text i Want more text if no separator then just remove tags

Which I think it's exactly what you want!

Upvotes: 0

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