src/Str.php
public static function upper($input, $encoding = self::DEFAULT_ENCODING)
    {
        return function_exists('mb_strtoupper')
            ? mb_strtoupper($input, $encoding)
            : strtoupper($input);
    }
public static function upper($input, $encoding = self::DEFAULT_ENCODING)
    {
        return function_exists('mb_strtoupper')
            ? mb_strtoupper($input, $encoding)
            : strtoupper($input);
    }
public static function upper ( $ input , $ encoding = self :: DEFAULT_ENCODING ) { return function_exists ( 'mb_strtoupper' ) ? mb_strtoupper ( $ input , $ encoding ) : strtoupper ( $ input ) ; }
Returns an uppercased string.

Returns an uppercased string. The $encoding parameter is used to determine the input string encoding
and thus use the proper method. The functions uses mb_strtoupper if present and falls back to strtoupper.

@author FuelPHP (http://fuelphp.com)

@param string $input    The input string
@param string $encoding The encoding of the input string

@return string The uppercased string
Returns an uppercased string .