chapter11-26.cpp

C++STL程序员开发指南

//文件名:CHAPTER11-26.cpp
#include <vector>
#include <set>
#include <algorithm>
#include <iostream>
#include <ostream>
using namespace std;
class CInt;
ostream& operator<<( ostream& osIn, const CInt& rhs );
class CInt
{
public:
   CInt( int n = 0 ) : m_nVal( n ){}
   CInt( const CInt& rhs ) : m_nVal( rhs.m_nVal ){}
   CInt& operator=( const CInt& rhs ) {m_nVal = 
   rhs.m_nVal; return *this;}
   bool operator<( const CInt& rhs ) const 
      {return ( m_nVal < rhs.m_nVal );}
   friend ostream& operator<<( ostream& osIn, const CInt& rhs );
private:
   int m_nVal;
};
inline ostream& operator<<(ostream& osIn, const CInt& rhs)
{
   osIn << "CInt( " << rhs.m_nVal << " )"; 
   return osIn;
}
// Return whether modulus of elem1 is greater than modulus of elem2
bool mod_lesser ( int elem1, int elem2 )
{
   if ( elem1 < 0 ) elem1 = - elem1;
   if ( elem2 < 0 ) elem2 = - elem2;
   return elem1 < elem2;
};
int main( )
{
   // Searching a set container with elements of type CInt for the maximum element 
   CInt c1 = 1, c2 = 2, c3 = -3;
   set<CInt> s1;
   set<CInt>::iterator s1_Iter, s1_R1_Iter, s1_R2_Iter;
   s1.insert ( c1 );
   s1.insert ( c2 );
   s1.insert ( c3 );
   cout << "s1 = (";
   for ( s1_Iter = s1.begin( ); s1_Iter != --s1.end( ); s1_Iter++ ) cout << " " << *s1_Iter << ",";
   s1_Iter = --s1.end( );
   cout << " " << *s1_Iter << " )." << endl;
   s1_R1_Iter = max_element ( s1.begin ( ) , s1.end ( ) );
   cout << "The largest element in s1 is: " << *s1_R1_Iter << endl;
   cout << endl;
   // Searching a vector with elements of type int for the maximum
   // element under default less than & mod_lesser binary predicates
   vector <int> v1;
   vector <int>::iterator v1_Iter, v1_R1_Iter, v1_R2_Iter;
   int i;
   for ( i = 0 ; i <= 3 ; i++ ) {v1.push_back( i );   }
   int ii;
   for ( ii = 1 ; ii <= 4 ; ii++ ) {v1.push_back( - 2 * ii );   }
   cout << "Vector v1 is ( " ;
   for ( v1_Iter = v1.begin( ) ; v1_Iter != v1.end( ) ; v1_Iter++ )
      cout << *v1_Iter << " ";
   cout << ")." << endl;
   v1_R1_Iter = max_element ( v1.begin ( ) , v1.end ( ) );
   v1_R2_Iter = max_element ( v1.begin ( ) , v1.end ( ), mod_lesser);
   cout << "The largest element in v1 is: " << *v1_R1_Iter << endl;
   cout << "The largest element in v1 under the mod_lesser"
        << "\n binary predicate is: " << *v1_R2_Iter << endl;
}