public function setFormat($format)
    {
        if (Format::isString256($format) === true) {
            $this->format = $format;
        } else {
            $msg = "The 'format' argument must be a string with at most 256 characters, '" . $format . "' given.";
            throw new InvalidArgumentException($msg);
        }
    }
public function setFormat($format)
    {
        if (Format::isString256($format) === true) {
            $this->format = $format;
        } else {
            $msg = "The 'format' argument must be a string with at most 256 characters, '" . $format . "' given.";
            throw new InvalidArgumentException($msg);
        }
    }
public function setFormat ( $ format ) { if ( Format :: isString256 ( $ format ) === true ) { $ this -> format = $ format ; } else { $ msg = "The 'format' argument must be a string with at most 256 characters, '" . $ format . "' given." ; throw new InvalidArgumentException ( $ msg ) ; } }
Set the format conversion to use when converting numerical values
to strings.

@param string $format See Number Formatting Rules for details.
@throws \InvalidArgumentException If $format is not a string with at most 256 characters.
@see http://www.imsglobal.org/question/qtiv2p1/imsqti_infov2p1.html#section10074
Set the format conversion to use when converting numerical values to strings .