Insert Iterator
An insert iterator used to insert items into a collection rather than overwrite the collection.
| Data Types |
| container_type |
| Member Functions |
| inserter() operator*() operator++() operator=() |
#include <iterator> template <class Container> class insert_iterator;
Insert iterators let you insert new elements into a collection rather than copy a new element's value over the value of an existing element. The class insert_iterator is used to insert items into a specified location of a collection. The function inserter creates an instance of an insert_iterator given a particular collection type and iterator. An insert_iterator can be used with vectors, deques, lists, maps and sets.
template <class Container>
class insert_iterator : public
iterator<output_iterator_tag,void,void,void,void> ; {
protected:
Container* container;
public:
typedef Container container_type;
insert_iterator (Container&, typename Container::iterator);
insert_iterator<Container>&
operator= (const typename Container::value_type&);
insert_iterator<Container>& operator* ();
insert_iterator<Container>& operator++ ();
insert_iterator<Container>& operator++ (int);
};
template <class Container, class Iterator>
insert_iterator<Container> inserter (Container&, Iterator)
container_type
The type of container acted on by the iterator.
insert_iterator(Container& x,
typename Container::iterator i);
Creates an instance of an insert_iterator associated with container x and iterator i.
insert_iterator<Container>& operator=(const typename Container::value_type& value);
Inserts a copy of value into the container at the location specified by the insert_iterator, increments the iterator, and returns *this.
insert_iterator<Container>& operator*();
Returns *this (the input iterator itself).
insert_iterator<Container>& operator++(); insert_iterator<Container>& operator++(int);
Increments the insert iterator and returns *this.
template <class Container, class Iterator> insert_iterator<Container> inserter(Container& x, Iterator i);
Returns an insert_iterator that inserts elements into container x at location i. This function allows you to create insert iterators inline.
#include <iterator>
#include <vector>
#include <iostream>
using namespace std;
int main()
{
//Initialize a vector using an array
int arr[4] = {3,4,7,8};
vector<int> v(arr,arr+4);
//Output the original vector
cout << "Start with a vector: " << endl << " ";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
//Insert into the middle
insert_iterator<vector<int> > ins(v, v.begin()+2);
*ins = 5;
*ins = 6;
//Output the new vector
cout << endl << endl;
cout << "Use an insert_iterator: " << endl << " ";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
return 0;
}
If your compiler does not support default template parameters, then you always need to supply the Allocator template argument. For instance, you have to write:
vector<int, allocator<int> >
instead of:
vector<int>
If your compiler does not support namespaces, then you do not need the using declaration for std.
back_insert_iterator, front_insert_iterator, Insert Iterators