How to replace specific numbers (within a length limit) with specific letters?

Question

I am trying to use preg_replace to change numbers to letters, but only numbers wrapped in "" and not more than 7 characters in the substring.

Sample input string:

"3"sca"""co"1"str"0"ctor""r"3"t"0"r"1""locat"5"o"133""0"27""754a49b393c2a0"33"b97"332"cb7"3"c3c07"2""co"1"str"0"ctor""r"3"t"0"

The desired effect is for every qualifying 2 to become d and every qualifying 3 to become e.

These are examples of correct replacements:

• "3" becomes e
• "23" becomes de
• "33" becomes ee
• "32" becomes de
• "333223" becomes eeedde

My coding attempt:

$string = preg_replace("/\"322\"+/", "edd", $string);
$string = preg_replace("/\"233\"+/", "dee", $string);
$string = preg_replace("/\"32\"+/", "ed", $string);
$string = preg_replace("/\"23\"+/", "de", $string);
$string = preg_replace("/\"33\"+/", "e", $string);
$string = preg_replace("/\"333\"+/", "e", $string);
$string = preg_replace("/\"3\"+/", "e", $string);
$string = preg_replace("/\"3\"+/", "e", $string);
$string = preg_replace("/\"3\"+/", "e", $string);
$string = preg_replace("/\"3\"+/", "e", $string);
$string = preg_replace("/\"3\"+/", "e", $string);

How can I make all qualifying replacements with one preg_replace call?

Answer 1

Use this regex to find either 2 or 3 between double-quotes from 1 to 7 times

(?<=\")[23]{1,7}(?=\")

"233223322" won't be replaced with "deeddeedd" because it has more than 7 characters (9)

Demo

Explanation

[23]{1,7} Either 2 or 3 from 1 to 7 times

(?<=\") Precedeed by a double-quote

(?=\") Followed by a double-quote

Snippet

$text = '"3"sca"""co"1"str"0"ctor""r"3"t"0"r"1""locat"5"o"133""0"27""754a49b393c2a0"33"b97"332"cb7"3"c3c07"2""co"1"str"0"ct"233223322"or""r"3"t"0"';

$regex = '/(?<=\")[23]{1,7}(?=\")/';

$text = preg_replace_callback($regex, 
    function ($m) {
        switch ($m[0]) {
            case '2': return 'd';
            case '3': return 'e';
            // Add other cases here ...
        }
    },
    $text
);

echo $text;

Online demo