TheAlgorithms-PHP/Strings/CheckAnagram.php

<?php

/**
 * Checks if two strings are anagrams of each other.
 *
 * @param string $originalString
 * @param string $testString
 * @param bool $caseInsensitive
 * @return bool
 */
function isAnagram(string $originalString, string $testString, bool $caseInsensitive = true)
{
    if ($caseInsensitive) {
        $originalString = strtolower($originalString); // Converting string to lowercase for case-insensitive check
        $testString = strtolower($testString);
    }

    // count_chars(string, mode = 1) returns key-value pairs with character as key, frequency as value
    // We can directly compare the arrays in this case
    return count_chars($originalString, 1) === count_chars($testString, 1);
}