C / C++ / MFC

template<class _Kty,
	class _Pr = less<_Kty> >
	class hash_compare
	{	// traits class for hash containers
public:
	enum
		{	// parameters for hash table
		bucket_size = 4,	// 0 < bucket_size
		min_buckets = 8};	// min_buckets = 2 ^^ N, 0 < N

	hash_compare()
		: comp()
		{	// construct with default comparator
		}

	hash_compare(_Pr _Pred)
		: comp(_Pred)
		{	// construct with _Pred comparator
		}

	size_t operator()(const _Kty& _Keyval) const
		{	// hash _Keyval to size_t value
		return (_Keyval);
		}

//	size_t operator()(const _Kty& _Keyval) const
//		{	// hash _Keyval to size_t value by pseudorandomizing transform
//		ldiv_t _Qrem = ldiv((size_t)_Keyval, 127773);
//		_Qrem.rem = 16807 * _Qrem.rem - 2836 * _Qrem.quot;
//		if (_Qrem.rem < 0)
//			_Qrem.rem += 2147483647;
//		return ((size_t)_Qrem.rem); }

	bool operator()(const _Kty& _Keyval1, const _Kty& _Keyval2) const
		{	// test if _Keyval1 ordered before _Keyval2
		return (comp(_Keyval1, _Keyval2));
		}

private:
	_Pr comp;	// the comparator object
	};

#include <hash_map>
#include <string>
using namespace std;

namespace std
{
template<> class hash_compare <string, less<string> >
{
public:
	enum
		{	// parameters for hash table
		bucket_size = 4,	// 0 < bucket_size
		min_buckets = 8};	// min_buckets = 2 ^^ N, 0 < N

	size_t operator()(const string& k) 
	{
		long val = 0;
		for (unsigned int i = 0; i < k.size(); ++i)
		{
			val += k.at(i);
		}
		return val;
	}

	bool operator()(const string& k1, const string& k2)
	{
		if (lstrcmp(k1.c_str(), k2.c_str()) <= 0) return false;
		return true;
	}

};
}

hash_map<string, string> maps;
maps["thomas"] = "george";
string val = maps["thomas"];

--------------------Configuration: test - Win32 Debug--------------------
Compiling...
StdAfx.cpp
Compiling...
MainFrm.cpp
c:\sxl\include\xhash(475) : error C2663: '()' : 2 overloads have no legal conversion for 'this' pointer
        c:\sxl\include\xhash(474) : while compiling class-template member function 'unsigned int __thiscall std::_Hash<class std::_Hmap_traits<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_s
tring<char,struct std::char_traits<char>,class std::allocator<char> >,class std::hash_compare<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,struct std::less<class std::basic_string<char,struct std::char_trai
ts<char>,class std::allocator<char> > > >,class std::allocator<struct std::pair<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const ,class std::basic_string<char,struct std::char_traits<char>,class std::allo
cator<char> > > >,0> >::_Hashval(const class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &) const'
c:\sxl\include\xhash(475) : error C2064: term does not evaluate to a function
        c:\sxl\include\xhash(474) : while compiling class-template member function 'unsigned int __thiscall std::_Hash<class std::_Hmap_traits<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_s
tring<char,struct std::char_traits<char>,class std::allocator<char> >,class std::hash_compare<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,struct std::less<class std::basic_string<char,struct std::char_trai
ts<char>,class std::allocator<char> > > >,class std::allocator<struct std::pair<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const ,class std::basic_string<char,struct std::char_traits<char>,class std::allo
cator<char> > > >,0> >::_Hashval(const class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &) const'
Generating Code...
Skipping... (no relevant changes detected)
test.cpp
testDoc.cpp
testView.cpp
Error executing cl.exe.

test.exe - 2 error(s), 0 warning(s)