hash_map::erase
Removes an element or a range of elements in a hash_map from specified positions or removes elements that match a specified key.
iterator erase(
iterator _Where
);
iterator erase(
iterator _First,
iterator _Last
);
size_type erase(
const key_type& _Key
);
Parameters
_Where
Position of the element to be removed from the hash_map._First
Position of the first element removed from the hash_map._Last
Position just beyond the last element removed from the hash_map._Key
The key value of the elements to be removed from the hash_map.
Return Value
For the first two member functions, a bidirectional iterator that designates the first element remaining beyond any elements removed, or a pointer to the end of the hash_map if no such element exists.
For the third member function, returns the number of elements that have been removed from the hash_map.
Remarks
The member functions never throw an exception.
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
When compiling this example with the /Wp64 flag or on a 64-bit platform, compiler warning C4267 will be generated. For more information on this warning, see Compiler Warning (level 3) C4267.
// hash_map_erase.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, hm2, hm3;
hash_map<int, int> :: iterator pIter, Iter1, Iter2;
int i;
hash_map<int, int>::size_type n;
typedef pair<int, int> Int_Pair;
for (i = 1; i < 5; i++)
{
hm1.insert(Int_Pair (i, i));
hm2.insert(Int_Pair (i, i*i));
hm3.insert(Int_Pair (i, i-1));
}
// The 1st member function removes an element at a given position
Iter1 = ++hm1.begin();
hm1.erase(Iter1);
cout << "After the 2nd element is deleted, the hash_map hm1 is:";
for (pIter = hm1.begin(); pIter != hm1.end(); pIter++)
cout << " " << pIter -> second;
cout << "." << endl;
// The 2nd member function removes elements
// in the range [_First, _Last)
Iter1 = ++hm2.begin();
Iter2 = --hm2.end();
hm2.erase(Iter1, Iter2);
cout << "After the middle two elements are deleted, "
<< "the hash_map hm2 is:";
for (pIter = hm2.begin(); pIter != hm2.end(); pIter++)
cout << " " << pIter -> second;
cout << "." << endl;
// The 3rd member function removes elements with a given _Key
n = hm3.erase(2);
cout << "After the element with a key of 2 is deleted,\n"
<< "the hash_map hm3 is:";
for (pIter = hm3.begin(); pIter != hm3.end(); pIter++)
cout << " " << pIter -> second;
cout << "." << endl;
// The 3rd member function returns the number of elements removed
cout << "The number of elements removed from hm3 is: "
<< n << "." << endl;
// The dereferenced iterator can also be used to specify a key
Iter1 = ++hm3.begin();
hm3.erase(Iter1);
cout << "After another element with a key equal to that"
<< endl;
cout << "of the 2nd element is deleted, "
<< "the hash_map hm3 is:";
for (pIter = hm3.begin(); pIter != hm3.end(); pIter++)
cout << " " << pIter -> second;
cout << "." << endl;
}
After the 2nd element is deleted, the hash_map hm1 is: 1 3 4.
After the middle two elements are deleted, the hash_map hm2 is: 1 16.
After the element with a key of 2 is deleted,
the hash_map hm3 is: 0 2 3.
The number of elements removed from hm3 is: 1.
After another element with a key equal to that
of the 2nd element is deleted, the hash_map hm3 is: 0 3.
Requirements
Header: <hash_map>
Namespace: stdext