# Re: How to use the "unsigned" representation of a number

From:
"Sylvester Hesp" <s.hesp@oisyn.nl>
Newsgroups:
comp.lang.c++
Date:
Mon, 14 May 2007 14:14:17 +0200
Message-ID:
<464852ac\$0\$336\$e4fe514c@news.xs4all.nl>
"FabioAng" <fabioangNOSPAM@libero.it> wrote in message
news:f29aga\$hfv\$1@nnrp-beta.newsland.it...

Is there a way to use always the "unsigned" representation, e.g.

template<typename InputType>
bool is_valid_xml_range(InputType input)
{
UnsignedInputType uinput = input;

if ( ( uinput >= 0x20 ) && ( uinput <= 0xD7FF ) )
return true;
else
return false;
}

You can do it via template specialization

template<class T> struct unsigned_type { typedef T type; };
template<> struct unsigned_type<char> { typedef unsigned char type; };
template<> struct unsigned_type<signed char> { typedef unsigned char
type; };
template<> struct unsigned_type<short> { typedef unsigned short type; };
template<> struct unsigned_type<int> { typedef unsigned int type; };
template<> struct unsigned_type<long> { typedef unsigned long type; };

template<typename InputType>
bool is_valid_xml_range(InputType input)
{
typedef unsigned_type<InputType>::type UnsignedInputType;
UnsignedInputType uinput = input;

if ( ( uinput >= 0x20 ) && ( uinput <= 0xD7FF ) )
return true;
else
return false;
}

- Sylvester

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