fig20_19.cpp

里面有很多关于编程的实用例子

// Fig. 20.19: fig20_19.cpp
// Testing Standard Library class multiset
#include <iostream>
using std::cout;
using std::endl;

#include <set> // multiset class-template definition

// define short name for multiset type used in this program
typedef std::multiset< int, std::less< int > > Ims;

#include <algorithm> // copy algorithm
#include <iterator> // ostream_iterator

int main()
{
   const int SIZE = 10;
   int a[ SIZE ] = { 7, 22, 9, 1, 18, 30, 100, 22, 85, 13 };
   Ims intMultiset; // Ims is typedef for "integer multiset"
   std::ostream_iterator< int > output( cout, " " );

   cout << "There are currently " << intMultiset.count( 15 )
      << " values of 15 in the multiset\n";
   
   intMultiset.insert( 15 ); // insert 15 in intMultiset
   intMultiset.insert( 15 ); // insert 15 in intMultiset
   cout << "After inserts, there are " << intMultiset.count( 15 )
      << " values of 15 in the multiset\n\n";

   // iterator that cannot be used to change element values
   Ims::const_iterator result;  

   // find 15 in intMultiset; find returns iterator
   result = intMultiset.find( 15 );  

   if ( result != intMultiset.end() ) // if iterator not at end
      cout << "Found value 15\n"; // found search value 15
   
   // find 20 in intMultiset; find returns iterator
   result = intMultiset.find( 20 );

   if ( result == intMultiset.end() ) // will be true hence
      cout << "Did not find value 20\n"; // did not find 20

   // insert elements of array a into intMultiset
   intMultiset.insert( a, a + SIZE ); 
   cout << "\nAfter insert, intMultiset contains:\n";
   std::copy( intMultiset.begin(), intMultiset.end(), output );

   // determine lower and upper bound of 22 in intMultiset
   cout << "\n\nLower bound of 22: " 
      << *( intMultiset.lower_bound( 22 ) );
   cout << "\nUpper bound of 22: " << *( intMultiset.upper_bound( 22 ) );

   // p represents pair of const_iterators 
   std::pair< Ims::const_iterator, Ims::const_iterator > p;

   // use equal_range to determine lower and upper bound 
   // of 22 in intMultiset
   p = intMultiset.equal_range( 22 );

   cout << "\n\nequal_range of 22:" << "\n   Lower bound: " 
      << *( p.first ) << "\n   Upper bound: " << *( p.second );
   cout << endl;
   return 0;
} // end main

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