//文件名:CHAPTER9-33.cpp
#include <set>
#include <iostream>
#if _MSC_VER > 1020   // if VC++ version is > 4.2
   using namespace std;  // std c++ libs implemented in std
#endif
int main( )
{
   set <int, less<int> > s1;
   set<int, less<int> >::key_compare kc1 = s1.key_comp( ) ;
   bool result1 = kc1( 2, 3 ) ;
   if( result1 == true )   
   {
      cout << "kc1( 2,3 ) returns value of true, "<< "where kc1 is the function object of s1."<< endl;
   }
   else   
   {
      cout << "kc1( 2,3 ) returns value of false "<< "where kc1 is the function object of s1." << endl;
   }
   set <int, greater<int> > s2;
   set<int, greater<int> >::key_compare kc2 = s2.key_comp( ) ;
   bool result2 = kc2( 2, 3 ) ;
   if(result2 == true)   
   {
      cout << "kc2( 2,3 ) returns value of true, "<< "where kc2 is the function object of s2." << endl;
   }
   else   
   {
      cout << "kc2( 2,3 ) returns value of false, "<< "where kc2 is the function object of s2." << endl;
   }
}