protected function unescapeControlCharacters($string)
    {
        $unescapedString = $string;

        foreach ($this->controlCharactersEscapingMap as $escapedCharValue => $charValue) {
            // only unescape characters that don't contain the escaped escape character for now
            $unescapedString = preg_replace("/(?<!_x005F)($escapedCharValue)/", $charValue, $unescapedString);
        }

        return $this->unescapeEscapeCharacter($unescapedString);
    }
protected function unescapeControlCharacters($string)
    {
        $unescapedString = $string;

        foreach ($this->controlCharactersEscapingMap as $escapedCharValue => $charValue) {
            // only unescape characters that don't contain the escaped escape character for now
            $unescapedString = preg_replace("/(?<!_x005F)($escapedCharValue)/", $charValue, $unescapedString);
        }

        return $this->unescapeEscapeCharacter($unescapedString);
    }
protected function unescapeControlCharacters ( $ string ) { $ unescapedString = $ string ; foreach ( $ this -> controlCharactersEscapingMap as $ escapedCharValue => $ charValue ) { // only unescape characters that don't contain the escaped escape character for now $ unescapedString = preg_replace ( "/(?<!_x005F)($escapedCharValue)/" , $ charValue , $ unescapedString ) ; } return $ this -> unescapeEscapeCharacter ( $ unescapedString ) ; }
Converts OpenXML escaped control characters from the given string to PHP control characters

Excel escapes control characters with _xHHHH_ and also escapes any
literal strings of that type by encoding the leading underscore.
So "_x0000_" -> "\0" and "_x005F_x0000_" -> "_x0000_"

NOTE: the logic has been adapted from the XlsxWriter library (BSD License)
@link https://github.com/jmcnamara/XlsxWriter/blob/f1e610f29/xlsxwriter/sharedstrings.py#L89

@param string $string String to unescape
@return string
Converts OpenXML escaped control characters from the given string to PHP control characters