[STL] Insert iterator or inserter)

1. Definition
The insert iterator is also called the inserter ).
2. Role
The main function of inserting an iterator is to convert a value assignment operation into an operation that inserts the corresponding value into the container.
The algorithm library imposes restrictions on all operations on the container: Never modify the container size (no insert or delete ). With the plug-in iterator, the algorithm library can insert new elements to the container through the iterator without violating this uniform band, that is, the design consistency is maintained.
3. Type
3.1 back_insert_iterator)
Use: Call the push_back () member function of the container to insert an element.
Function: Insert elements at the end of the container.
Restriction: Only containers that provide push_back () member functions
Applicable: vector deque list
3.2 front_insert_iterator)
Use: Call the push_front () member function of the container to insert an element.
Function: Insert elements at the front end of the container.
Restriction: Only containers that provide push_front () member functions
Applicable: deque list
3.3 insert_iterator)
Use: insert an element by calling the insert () member function, and specify the insert position.
Function: insert an element at the specified position of the container.
Restriction: All STL containers provide the insert () function.
Applicable: All STL containers
4. Example

# Include <iostream> # include <vector> # include <list> # include <iterator> using namespace STD; Template <typename T> void printelements (t C) {T :: const_iterator itr = C. begin (); While (itr! = C. end () cout <* itr ++ <"" ;}int main () {vector <int> vecsrc; List <int> vecdest; for (vector <int >:: size_type I = 0; I <3; ++ I) vecsrc. push_back (I); // 1. class handler and function back_inserter // explicit back_insert_iterator (container & _ cont); // template <class container> back_insert_iterator <container> back_inserter (container & _ cont); copy (vecsrc. begin (), vecsrc. end (), back_insert_iterator <list <int> (vecdest); // copy (vecsrc. begin (), vecsrc. end (), back_inserter (vecdest); // printelements (vecdest); cout <Endl; // 2. class delimiter and function front_inserter // explicit front_insert_iterator (container & _ cont); // template <class container> front_insert_iterator <container> front_inserter (container & _ cont); copy (vecsrc. begin (), vecsrc. end (), front_insert_iterator <list <int> (vecdest); // copy (vecsrc. begin (), vecsrc. end (), front_inserter (vecdest); printelements (vecdest); cout <Endl; // 3. class insert_iterator and function inserter // insert_iterator (container & _ cont, typename container: iterator _ it ); // template <class container> insert_iterator <container> inserter (container & _ cont, typename container: iterator _ Where); copy (vecsrc. begin (), vecsrc. end (), insert_iterator <list <int> (vecdest, ++ vecdest. begin (); // copy (vecsrc. begin (), vecsrc. end (), inserter (vecdest, ++ vecdest. begin (); printelements (vecdest); Return 0 ;}

Running result:

0 1 22 1 0 0 1 22 0 1 2 1 0 1 2 press any key to continue.