CODEWITHSUNDEEP
phpstringreplace
Kamini
Kamini

Reputation: 393

Remove Same Character once from two different string

I need help in PHP Script.

I have two strings.

$string1 = "asdfgf";
$string2 = "asdfgasdg";

After removing the same character from both string once,

$string1 = "f";
$string2 = "asdg";

Another Two Strings example

$string1 = "sthnfr";
$string2 = "iserr";

Output

$string1 = "thnf"; // s and r removed
$string2 = "ier"; // s and r removed

I tried str_replace which replace all the all the characters. Thanks for your helps

Upvotes: 0

Views: 621

Answers (2)

mickmackusa
mickmackusa

Reputation: 47904

  1. Iterate each character in the first string (use mb_str_split() from PHP7.4 if you are processing strings with multibyte characters).

  2. Replace the first occurrence of the isolated character in the second string with an empty string; limit the replacements to 1; and temporarily store the the success of the replacement in $count. preg_quote() is used to stabilize the pattern and protect it from characters with special meaning to the regex engine. Again, if multibyte characters are possible, add the u pattern modifier after the last / in the first parameter of preg_replace().

  3. If $count is 0, then there was no match and the isolated character should be appended to the iteratively rebuilt $newA string.

Using this technique, the first string only grows larger as not-found characters are encountered and the second string only gets smaller as found characters are encountered. In other words, for every character iterated, either the seconds string loses a character or the new first string gains a character.

This technique is built to sanitize shared characters in both strings regardless of the order/position of the characters in the strings. It is also very easy to extend to cover multibyte scenarios.

Function: (Demo)

function removeSharedCharacters(string $a, string $b): array {
    $newA = '';
    foreach (str_split($a) as $char) {
        $b = preg_replace('/' . preg_quote($char, '/') . '/', '', $b, 1, $count);
        if (!$count) {
            $newA .= $char;
        }
    }
    return [$newA, $b];    
}

Test cases and function call:

$tests = [
    ["asdfgf", "asdfgasdg"],
    ["sthnfr", "iserr"],
    ["acegik", "jihgfedcba"]
];

foreach ($tests as $pair) {
    var_export(removeSharedCharacters(...$pair));
    echo "\n---\n";
}

Output:

array (
  0 => 'f',
  1 => 'asdg',
)
---
array (
  0 => 'thnf',
  1 => 'ier',
)
---
array (
  0 => 'k',
  1 => 'jhfdb',
)
---

Upvotes: 0

user142162
user142162

Reputation: 

$string2 = "sthnfr";
$string1 = "iserr";

for($i = 0; $i < strlen($string1); )
{
    if(($pos = strpos($string2, $string1[$i])) !== false)
    {
        $string1 = substr($string1, 0, $i) . substr($string1, $i + 1);
        $string2 = substr($string2, 0, $pos) . substr($string2, $pos + 1);
        continue;
    }
    $i++;
}

Upvotes: 1

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