Namespaces
Variants

    cpp/iterator/back insert iterator: Difference between revisions

    From cppreference.com
    ← Older edit
    m link concept, shorten a line
    Space Mission (talk | contribs)
    19,914 edits
    m fmt.
     
    (19 intermediate revisions by 14 users not shown)
    Line 1: Line 1:
    {{cpp/title|back_insert_iterator}}
    {{cpp/title|back_insert_iterator}}
    {{cpp/iterator/back_insert_iterator/navbar}}
    {{cpp/iterator/back_insert_iterator/navbar}}
    {{ddcl list begin}}
    {{begin}}
    {{ddcl list header | iterator}}
    {{header|iterator}}
    {{ddcl list item | 1=
    {{
    |1=
    template< class Container >
    template< class Container >
    class back_insert_iterator : public std::iterator< std::output_iterator_tag,
    class back_insert_iterator
                                                      void,void,void,void >
    : public std::iterator<std::output_iterator_tag, void, void, void, void>
    }}
    }}
    {{ddcl list end}}
    {{
    end}}


    {{tt|std::back_insert_iterator}} is an {{concept|OutputIterator}} that appends to a container for which it was constructed, using the container's {{tt|push_back()}} member function whenever the iterator (whether dereferenced or not) is assigned to. Incrementing the {{tt|std::back_insert_iterator}} is a no-op.
    {{tt|std::back_insert_iterator}} is {{|OutputIterator}} that appends to a container for which it was constructedcontainer's {{tt|push_back()}} member function whenever the iterator (whether dereferenced or not) is assigned to. Incrementing the {{tt|std::back_insert_iterator}} is a no-op.


    ===Member types===
    {{||
    {{dcl list begin}}
    {{|{{tt|container_type}}|{{tt|Container}}}}
    {{dcl list hitem | Member type | Definition}}
    }}
    {{dcl list item | {{tt|container_type}} | {{tt|Container}}}}
    {{dcl list end}}


    ===Member functions===
    ===Member functions===
    {{dcl list begin}}
    {{begin}}
    {{dcl list template | cpp/iterator/inserter/dcl list constructor | back_insert_iterator}}
    {{|cpp/iterator/inserter/constructor|back_insert_iterator}}
    {{dcl list template | cpp/iterator/inserter/dcl list operator{{=}} | back_insert_iterator}}
    {{|cpp/iterator/inserter/operator{{=}}|back_insert_iterator}}
    {{dcl list template | cpp/iterator/inserter/dcl list operator* | back_insert_iterator}}
    {{|cpp/iterator/inserter/operator*|back_insert_iterator}}
    {{dcl list template | cpp/iterator/inserter/dcl list operator++ | back_insert_iterator}}
    {{|cpp/iterator/inserter/|back_insert_iterator}}
    {{dcl list end}}
    {{end}}


    ===Member objects===
    ===Member objects===
    {{dcl list begin}}
    {{begin}}
    {{dcl list hitem | Member name | Definition}}
    {{hitem|Member name|Definition}}
    {{dcl list item | {{tt|container}} {{mark|protected}} | a pointer of type {{tt|Container*}} }}
    {{|{{tt|container}} {{mark|protected}}|a pointer of type {{tt|Container*}}}}
    {{dcl list end}}
    {{end}}
     
    {{cpp/iterator/iterator/inherit|std::output_iterator_tag|void|void|void|void}}


    ===Example===
    ===Example===
    {{example
    {{example
    |
    |code=
    | code=
    #include <iostream>
    #include <iostream>
    #include <iterator>
    #include <iterator>
    #include <algorithm>
    #include <>
    #include <cstdlib>
     
    int main()
    int main()
    {
    {
         std::vector<int> v;
         std::vector<int> v;
         std::generate_n(std::back_insert_iterator<std::vector<int>>(v), // can be simplified
     
                        10, [](){return std::rand()%10;});       // with std::back_inserter
         std::generate_n(
         for(int n : v)
    std::back_insert_iterator<std::vector<int>>(v),
    //
    10,
    []() { return ; }
    );
     
         for (int n : v)
             std::cout << n << ' ';
             std::cout << n << ' ';
         std::cout << '\n';
         std::cout << '\n';
    }
    }
    | output=
    |output=
    3 6 7 5 3 5 6 2 9 1
    3 6 7 9
    }}
    }}


    ===See also===
    ===See also===
    {{dcl list begin}}
    {{begin}}
    {{dcl list template | cpp/iterator/dcl list back_inserter}}
    {{|cpp/iterator/back_inserter}}
    {{dcl list template | cpp/iterator/dcl list front_insert_iterator}}
    {{|cpp/iterator/front_insert_iterator}}
    {{dcl list template | cpp/iterator/dcl list insert_iterator}}
    {{|cpp/iterator/insert_iterator}}
    {{dcl list end}}
    {{end
     
    }}

    Latest revision as of 16:26, 18 September 2023

     
    C++
     
    Iterator library
    Iterator concepts
    Iterator primitives
    Algorithm concepts and utilities
    Indirect callable concepts
    Common algorithm requirements
    (C++20)
    (C++20)
    (C++20)
    Utilities
    (C++20)
    Iterator adaptors
    Range access
    (C++11)(C++14)
    (C++14)(C++14)  
    (C++11)(C++14)
    (C++14)(C++14)  
    (C++17)(C++20)
    (C++17)
    (C++17)
     
    std::back_insert_iterator
     
    Defined in header <iterator> 
    template< class Container >
class back_insert_iterator
    : public std::iterator<std::output_iterator_tag, void, void, void, void>
    		(until C++17) 
    template< class Container >
class back_insert_iterator;
    		(since C++17)

    std::back_insert_iterator is a LegacyOutputIterator that appends elements to a container for which it was constructed. The container's push_back() member function is called whenever the iterator (whether dereferenced or not) is assigned to. Incrementing the std::back_insert_iterator is a no-op.

    Member types

    Member type Definition
    iterator_category std::output_iterator_tag
    value_type void
    difference_type

    void

    		(until C++20)

    std::ptrdiff_t

    		(since C++20)
    pointer void
    reference void
    container_type Container

    Member types iterator_category, value_type, difference_type, pointer and reference are required to be obtained by inheriting from std::iterator<std::output_iterator_tag, void, void, void, void>.

    		(until C++17)

    Member functions

    		 constructs a new back_insert_iterator
    (public member function) [edit]
    		inserts an object into the associated container
    (public member function) [edit]