user_defined stl::basic_string traits

ichar_traits.cpp

using std::basic_string;
using std::char_traits;
using std::string;
using std::toupper;;

struct ichar_traits : char_traits<char> 
{
    static bool eq(const char& _Left, const char& _Right)
	{
		return toupper(_Left) == toupper(_Right);
	}

	static bool lt(const char& _Left, const char& _Right)
	{
		return toupper(_Left) < toupper(_Right);
	}

	static int compare(const char_type* _Str1, const char_type* _Str2, size_t _Num )
	{
		const char_type* ps1 = _Str1;
		const char_type* ps2 = _Str2;

		for (size_t i = 0; i < _Num; ++i)
		{
			if (ps1 == NULL)
			{
				return -1;
			}
			else if (ps2 == NULL)
			{
				return 1;
			}
			else if (toupper(*ps1) < toupper(*ps2))
			{
				return -1;
			}
			else if (toupper(*ps1) > toupper(*ps2))
			{
				return 1;	
			}

			assert(toupper(*ps1) == toupper(*ps2));
			++ps1;
			++ps2;
		}

		return 0;
	}
};

typedef basic_string<char, ichar_traits> istring;