hash_multimap::equal_range

Returns a pair of iterators respectively to the first element in a hash_multimap with a key that is greater than a specified key and to the first element in the hash_multimap with a key that is equal to or greater than the key.

pair <const_iterator, const_iterator> equal_range ( 
   const Key& _Key 
) const; 
pair <iterator, iterator> equal_range ( 
   const Key& _Key 
);

Parameters

• _Key
  The argument key to be compared with the sort key of an element from the hash_multimap being searched.

Return Value

A pair of iterators such that the first is the lower_bound of the key and the second is the upper_bound of the key.

To access the first iterator of a pair pr returned by the member function, use pr.first and to dereference the lower bound iterator, use *(pr.first). To access the second iterator of a pair pr returned by the member function, use pr.second and to dereference the upper bound iterator, use *(pr.second).

Remarks

In Visual C++ .NET 2003, members of the <hash_map> and <hash_set> header files are no longer in the std namespace, but rather have been moved into the stdext namespace. See The stdext Namespace for more information.

Example

// hash_multimap_equal_range.cpp
// compile with: /EHsc
#include <hash_map>
#include <iostream>

int main( )
{
   using namespace std;
   using namespace stdext;
   typedef hash_multimap <int, int> IntMMap;
   IntMMap hm1;
   hash_multimap <int, int> :: const_iterator hm1_RcIter;
   typedef pair <int, int> Int_Pair;

   hm1.insert ( Int_Pair ( 1, 10 ) );
   hm1.insert ( Int_Pair ( 2, 20 ) );
   hm1.insert ( Int_Pair ( 3, 30 ) );

   pair <IntMMap::const_iterator, IntMMap::const_iterator> p1, p2;
   p1 = hm1.equal_range( 2 );

   cout << "The lower bound of the element with "
        << "a key of 2\n in the hash_multimap hm1 is: "
        << p1.first -> second << "." << endl;

   cout << "The upper bound of the element with "
        << "a key of 2\n in the hash_multimap hm1 is: "
        << p1.second -> second << "." << endl;

   // Compare the upper_bound called directly 
   hm1_RcIter = hm1.upper_bound( 2 );

   cout << "A direct call of upper_bound( 2 ) gives "
        << hm1_RcIter -> second << "," << endl
        << " matching the 2nd element of the pair"
        << " returned by equal_range( 2 )." << endl;

   p2 = hm1.equal_range( 4 );

   // If no match is found for the key,
   // both elements of the pair return end( )
   if ( ( p2.first == hm1.end( ) ) && ( p2.second == hm1.end( ) ) )
      cout << "The hash_multimap hm1 doesn't have an element "
           << "with a key less than 4." << endl;
   else
      cout << "The element of hash_multimap hm1 with a key >= 40 is: "
           << p1.first -> first << "." << endl;
}

The lower bound of the element with a key of 2
 in the hash_multimap hm1 is: 20.
The upper bound of the element with a key of 2
 in the hash_multimap hm1 is: 30.
A direct call of upper_bound( 2 ) gives 30,
 matching the 2nd element of the pair returned by equal_range( 2 ).
The hash_multimap hm1 doesn't have an element with a key less than 4.

Requirements

Header: <hash_map>

Namespace: stdext

See Also

Reference

hash_multimap Class

Standard Template Library