Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.

NAME

 
back_insert_iterator, back_inserter
 
 - An insert iterator used to insert items at the end of a collection.
 
 
 

SYNOPSIS

 
 
#include <iterator>
template <class Container>
class back_insert_iterator;
 
 
 

DESCRIPTION

 
 
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_back_insert_iterator is used to insert items at the end of a collection. The function back_inserter creates an instance of a back_insert_iterator for a particular collection type. A back_insert_iterator can be used with vectors, deques, and lists, but not with maps or sets. 
 
 
 

INTERFACE

 
 
 
template <class Container>
class back_insert_iterator

: public iterator <output_iterator_tag, void, void, void,

void> {

 
protected:

Container∗ container;

public:

typedef Container container_type;
explicit back_insert_iterator (Container&);
back_insert_iterator<Container>&

operator=

(const typename Container::const_reference value);

back_insert_iterator<Container>& operator∗ ();
back_insert_iterator<Container>& operator++ ();
back_insert_iterator<Container> operator++ (int);

};
 
template <class Container>
back_insert_iterator<Container> back_inserter (Container&);
 
 
 

TYPES

 
 
 
container_type
 

 
The type of container acted on by this iterator.
 

CONSTRUCTORS

 
 
 
explicit
back_insert_iterator (Container& x);

 
 
Constructor. Creates an instance of a back_insert_iterator associated with container x.
 

OPERATORS

 
 
 
back_insert_iterator<Container>&
operator= (const typename Container::value_type& value);

 
 
Inserts a copy of value on the end of the container, and returns ∗this. 
 

 
 
back_insert_iterator<Container>&
operator∗ ();

 
 
Returns ∗this. 
 

 
 
back_insert_iterator<Container>&
operator++ ();
back_insert_iterator<Container>
operator++ (int);

 
 
Increments the input iterator and returns ∗this. 
 

HELPER FUNCTIONS

 
 
 
template <class Container>
back_insert_iterator<Container>
back_inserter (Container& x)

 
 
Returns a back_insert_iterator that inserts elements at the end of container x. This function allows you to create insert iterators inline. 
 

EXAMPLE

 
 
 
//
// ins_itr.cpp
//

#include <iterator>
#include <deque>
#include <iostream>

using namespace std;
 
int main ()

{

//
// Initialize a deque using an array.
//

int arr[4] = { 3,4,7,8 };
deque<int> d(arr+0, arr+4);

//
// Output the original deque.
//

cout << "Start with a deque: " << endl << "     ";
copy(d.begin(), d.end(),

ostream_iterator<int,char>(cout," "));

//
// Insert into the middle.
//

insert_iterator<deque<int> > ins(d, d.begin()+2);

∗ins = 5; ∗ins = 6;
//
// Output the new deque.
//

cout << endl << endl;
cout << "Use an insert_iterator: " << endl << "     ";
copy(d.begin(), d.end(),

ostream_iterator<int,char>(cout," "));

//
// A deque of four 1s.
//

deque<int> d2(4, 1);

//
// Insert d2 at front of d.
//

copy(d2.begin(), d2.end(), front_inserter(d));

//
// Output the new deque.
//

cout << endl << endl;
cout << "Use a front_inserter: " << endl << "     ";
copy(d.begin(), d.end(),

ostream_iterator<int,char>(cout," "));

//
// Insert d2 at back of d.
//

copy(d2.begin(), d2.end(), back_inserter(d));

//
// Output the new deque.
//

cout << endl << endl;
cout << "Use a back_inserter: " << endl << "     ";
copy(d.begin(), d.end(),

ostream_iterator<int,char>(cout," "));

cout << endl;

return 0;

}
 

Program Output
 
 
 

 
Start with a deque:

3 4 7 8

Use an insert_iterator:

3 4 5 6 7 8

Use a front_inserter:

1 1 1 1 3 4 5 6 7 8

Use a back_inserter:

1 1 1 1 3 4 5 6 7 8 1 1 1 1
 
 
 

WARNINGS

 
 
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. 
 
 
 

SEE ALSO

 
 
Insert_Iterators
 

Rogue Wave Software  —  Last change: 02 Apr 1998