Re: How to obtain a typedef for the unsigned version of a signed character type

From:

red floyd <no.spam.here@its.invalid>

Newsgroups:

comp.lang.c++.moderated

Date:

Sun, 7 Mar 2010 23:07:42 CST

Message-ID:

<hn1i91$jtn$1@news.eternal-september.org>

On 3/7/2010 2:01 PM, JohnW wrote:

I want to obtain a typedef for the unsigned version of a signed
character type. The example below demonstrates the problem, I have a
typedef for a signed character type but don't know how to obtain the
corresponding unsigned type.

template< class string_t>
struct Example
{
      typedef typename string_t::value_type char_t;
      typedef unsigned char_t uchar_t; // doesn't compile

      // ...
};

template<typename T> struct to_unsigned;
template<>
struct to_unsigned<char>
{
    typedef unsigned char unsigned_t;
};

template<>
struct to_unsigned<wchar_t>
{
   typedef unsigned wchar_t unsigned_t;
};

template<>
struct to_unsigned<short>
{
   typedef unsigned short unsigned_t;
};

template<>
struct to_unsigned<int>
{
   typedef unsigned int unsigned_t;
}

template<>
struct to_unsigned<long>
{
   typedef unsigned long unsigned_t;
};

struct Example
{
       typedef typename string_t::value_type char_t;
       typedef typename to_unsigned<char_t>::unsigned_t uchar_t;

       // ...
};

--
      [ See http://www.gotw.ca/resources/clcm.htm for info about ]
      [ comp.lang.c++.moderated. First time posters: Do this! ]