voku / portable-utf8

   *

   * @return string|false The portion of haystack or false if needle is not found.

   */

  public static function strrchr(string $haystack, string $needle, bool $before_needle = false, string $encoding = 'UTF-8', bool $cleanUtf8 = false)

  {

    if ($encoding !== 'UTF-8' && $encoding !== 'CP850') {

      $encoding = self::normalize_encoding($encoding, 'UTF-8');

    }

    if ($cleanUtf8 === true) {

      // "\mb_strpos" and "\iconv_strpos" returns wrong position,

      // if invalid characters are found in $haystack before $needle

      $needle = self::clean($needle);

      $haystack = self::clean($haystack);

    }

    // fallback to "mb_"-function via polyfill

    return \mb_strrchr($haystack, $needle, $before_needle, $encoding);

  }

  /**

   * Reverses characters order in the string.

   *

   * @return string|false <p>The portion of haystack or<br>false if needle is not found.</p>

   */

  public static function strrichr(string $haystack, string $needle, bool $before_needle = false, string $encoding = 'UTF-8', bool $cleanUtf8 = false)

  {

    if ($encoding !== 'UTF-8' && $encoding !== 'CP850') {

      $encoding = self::normalize_encoding($encoding, 'UTF-8');

    }

    if ($cleanUtf8 === true) {

      // "\mb_strpos" and "\iconv_strpos" returns wrong position,

      // if invalid characters are found in $haystack before $needle

      $needle = self::clean($needle);

      $haystack = self::clean($haystack);

    }

    return \mb_strrichr($haystack, $needle, $before_needle, $encoding);

  }

  /**

   * Find position of last occurrence of a case-insensitive string.