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<?php
 namespace Anzawi\FindDiff;
 
 class Hamming
 {
 /**
 * Calculate Hamming distance between two strings
 * Note: In its simplest form the function will take only the two strings
 * as parameter and will calculate just the number
 * @param string $firstString One of the strings being evaluated for Hamming distance.
 * @param string $secondString One of the strings being evaluated for Hamming distance.
 * @return int
 */
 public static function calculate(string $firstString, string $secondString): int
 {
 $i = 0;
 $count = 0;
 while (isset($firstString[$i]) != '') {
 if (isset($firstString[$i]) && isset($secondString[$i])) {
 if ($firstString[$i] != $secondString[$i]) {
 $count++;
 }
 }
 $i++;
 }
 return $count;
 }
 }
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