hash_map::begin
Returns an iterator addressing the first element in the hash_map.
const_iterator begin( ) const;
iterator begin( );
Return Value
A bidirectional iterator addressing the first element in the hash_map or the location succeeding an empty hash_map.
Remark
If the return value of begin is assigned to a const_iterator, the elements in the hash_map object cannot be modified. If the return value of begin is assigned to an iterator, the elements in the hash_map object can be modified.
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_map_begin.cpp
// compile with: /EHsc
#define _DEFINE_DEPRECATED_HASH_CLASSES 0
#include <hash_map>
#include <iostream>
int main( )
{
using namespace std;
using namespace stdext;
hash_map <int, int> hm1;
hash_map <int, int> :: iterator hm1_Iter;
hash_map <int, int> :: const_iterator hm1_cIter;
typedef pair <int, int> Int_Pair;
hm1.insert ( Int_Pair ( 0, 0 ) );
hm1.insert ( Int_Pair ( 1, 1 ) );
hm1.insert ( Int_Pair ( 2, 4 ) );
hm1_cIter = hm1.begin ( );
cout << "The first element of hm1 is "
<< hm1_cIter -> first << "." << endl;
hm1_Iter = hm1.begin ( );
hm1.erase ( hm1_Iter );
// The following 2 lines would err because the iterator is const
// hm1_cIter = hm1.begin ( );
// hm1.erase ( hm1_cIter );
hm1_cIter = hm1.begin( );
cout << "The first element of hm1 is now "
<< hm1_cIter -> first << "." << endl;
}
The first element of hm1 is 0.
The first element of hm1 is now 1.
Requirements
Header: <hash_map>
Namespace: stdext