hash_set::rbegin
Note
This API is obsolete. The alternative is unordered_set Class.
Returns an iterator addressing the first element in a reversed hash_set.
const_reverse_iterator rbegin( ) const;
reverse_iterator rbegin( );
Return Value
A reverse bidirectional iterator addressing the first element in a reversed hash_set or addressing what had been the last element in the unreversed hash_set.
Remarks
rbegin is used with a reversed hash_set just as begin is used with a hash_set.
If the return value of rbegin is assigned to a const_reverse_iterator, then the hash_set object cannot be modified. If the return value of rbegin is assigned to a reverse_iterator, then the hash_set object can be modified.
rbegin can be used to iterate through a hash_set backwards.
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_set_rbegin.cpp
// compile with: /EHsc
#include <hash_set>
#include <iostream>
int main( )
{
using namespace std;
using namespace stdext;
hash_set <int> hs1;
hash_set <int>::iterator hs1_Iter;
hash_set <int>::reverse_iterator hs1_rIter;
hs1.insert( 10 );
hs1.insert( 20 );
hs1.insert( 30 );
hs1_rIter = hs1.rbegin( );
cout << "The first element in the reversed hash_set is "
<< *hs1_rIter << "." << endl;
// begin can be used to start an iteration
// throught a hash_set in a forward order
cout << "The hash_set is: ";
for ( hs1_Iter = hs1.begin( ) ; hs1_Iter != hs1.end( );
hs1_Iter++ )
cout << *hs1_Iter << " ";
cout << endl;
// rbegin can be used to start an iteration
// throught a hash_set in a reverse order
cout << "The reversed hash_set is: ";
for ( hs1_rIter = hs1.rbegin( ) ; hs1_rIter != hs1.rend( );
hs1_rIter++ )
cout << *hs1_rIter << " ";
cout << endl;
// A hash_set element can be erased by dereferencing to its key
hs1_rIter = hs1.rbegin( );
hs1.erase ( *hs1_rIter );
hs1_rIter = hs1.rbegin( );
cout << "After the erasure, the first element "
<< "in the reversed hash_set is "<< *hs1_rIter << "."
<< endl;
}
The first element in the reversed hash_set is 30. The hash_set is: 10 20 30 The reversed hash_set is: 30 20 10 After the erasure, the first element in the reversed hash_set is 20.
Requirements
Header: <hash_set>
Namespace: stdext