ltstr.h

#ifndef _Ltstr_
#define _Ltstr_

#include <string>
#include <cwchar>
#include <cstring>

using namespace std;

struct Ltstr
{
  bool operator()(string const &s1, string const &s2) const
  {
    return strcmp(s1.c_str(), s2.c_str()) < 0;
  }

  bool operator()(wchar_t const *s1, wchar_t const *s2) const
  {
    return wcscmp(s1, s2) < 0;
  }

  bool operator()(char const *s1, char const *s2) const
  {
    return strcmp(s1, s2) < 0;
  }

  bool operator()(wstring const &s1, wstring const &s2) const
  {
    return wcscmp(s1.c_str(), s2.c_str()) < 0;
  }
};

#endif