raynaldmo / php-education Goto Github PK

There is a bug in your Jaro-Winkler method. A compared to B will yield a different result to B compared to A, when either A or B is a string where a character found in both strings is found more than once in one string.

To rectify this, when identifying common characters, the same character should not be repeated. The common characters variable needs to be deduplicated before returned.

The below code replaces the common characters string with an array that uses the common character as the key, to avoid duplication. By using the code below, A compared to B yields the same results as B compared to A.

This is in line with the C# version of the method.

//$commonCharacters='';
$commonCharacters = [];
for( $i=0; $i < $str1_len; $i++){
	$noMatch = True;
	// compare if char does match inside given allowedDistance
	// and if it does add it to commonCharacters
	for( $j= max( 0, $i-$allowedDistance ); $noMatch && $j < min( $i + $allowedDistance + 1, $str2_len ); $j++) {
		if( $temp_string2[(int)$j] == $string1[$i] ){ // MJR
			$noMatch = False;
			//$commonCharacters .= $string1[$i];
			$commonCharacters[$string1[$i]] = $string1[$i];
			$temp_string2[(int)$j] = ''; // MJR
		}
	}
}
//return $commonCharacters;
return implode("", $commonCharacters);