Difference between revisions of "cpp/container/multimap/insert"

Latest revision as of 13:53, 10 January 2024

iterator insert( const value_type& value );	(1)
iterator insert( value_type&& value );	(2)	(since C++17)
template< class P > iterator insert( P&& value );	(3)	(since C++11)
	(4)
iterator insert( iterator pos, const value_type& value );			(until C++11)
iterator insert( const_iterator pos, const value_type& value );			(since C++11)
iterator insert( const_iterator pos, value_type&& value );		(5)	(since C++17)
template< class P > iterator insert( const_iterator pos, P&& value );		(6)	(since C++11)
template< class InputIt > void insert( InputIt first, InputIt last );		(7)
void insert( std::initializer_list<value_type> ilist );		(8)	(since C++11)
iterator insert( node_type&& nh );		(9)	(since C++17)
iterator insert( const_iterator pos, node_type&& nh );		(10)	(since C++17)

Inserts element(s) into the container.

1-3) Inserts value. If the container has elements with equivalent key, inserts at the upper bound of that range.

Overload (3) is equivalent to emplace(std::forward<P>(value)) and only participates in overload resolution if std::is_constructible<value_type, P&&>::value == true.

4-6) Inserts value in the position as close as possible to the position just prior to pos.

Overload (6) is equivalent to emplace_hint(hint, std::forward<P>(value)) and only participates in overload resolution if std::is_constructible<value_type, P&&>::value == true.

7) Inserts elements from range [first, last).

8) Inserts elements from initializer list ilist.

9) If nh is an empty node handle, does nothing. Otherwise, inserts the element owned by nh into the container and returns an iterator pointing at the inserted element. If a range containing elements with keys equivalent to nh.key() exists in the container, the element is inserted at the end of that range. The behavior is undefined if nh is not empty and get_allocator() != nh.get_allocator().

10) If nh is an empty node handle, does nothing and returns the end iterator. Otherwise, inserts the element owned by nh into the container, and returns the iterator pointing to the element with key equivalent to nh.key(). The element is inserted as close as possible to the position just prior to pos. The behavior is undefined if nh is not empty and get_allocator() != nh.get_allocator().

No iterators or references are invalidated. If the insertion is successful, pointers and references to the element obtained while it is held in the node handle are invalidated, and pointers and references obtained to that element before it was extracted become valid.(since C++17)

#include <functional>
#include <iostream>
#include <map>
#include <string>
#include <string_view>
#include <utility>
 
template<class M>
void print(const std::string_view rem, const M& mmap)
{
    std::cout << rem << ' ';
    for (const auto& e : mmap)
        std::cout << '{' << e.first << ',' << e.second << "} ";
    std::cout << '\n';
}
 
int main()
{
    // list-initialize
    std::multimap<int, std::string, std::greater<int>> mmap
        {{2, "foo"}, {2, "bar"}, {3, "baz"}, {1, "abc"}, {5, "def"}};
    print("#1", mmap);
 
    // insert using value_type
    mmap.insert(decltype(mmap)::value_type(5, "pqr"));
    print("#2", mmap);
 
    // insert using pair
    mmap.insert(std::pair{6, "uvw"});
    print("#3", mmap);
 
    mmap.insert({7, "xyz"});
    print("#4", mmap);
 
    // insert using initializer_list
    mmap.insert({{5, "one"}, {5, "two"}});
    print("#5", mmap);
 
    // insert using a pair of iterators
    mmap.clear();
    const auto il = {std::pair{1, "ä"}, {2, "ё"}, {2, "ö"}, {3, "ü"}};
    mmap.insert(il.begin(), il.end());
    print("#6", mmap);
}

Output:

#1 {5,def} {3,baz} {2,foo} {2,bar} {1,abc}
#2 {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
#3 {6,uvw} {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
#4 {7,xyz} {6,uvw} {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
#5 {7,xyz} {6,uvw} {5,def} {5,pqr} {5,one} {5,two} {3,baz} {2,foo} {2,bar} {1,abc}
#6 {3,ü} {2,ё} {2,ö} {1,ä}

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 233	C++98	pos was just a hint, it could be totally ignored	the insertion is required to be as close as possible to the position just prior to pos
LWG 264	C++98	the complexity of overload (5) was required to be linear if the range `[`first`,` last`)` is sorted according to `Compare`	removed the linear requirement in this special case
LWG 371	C++98	the order of equivalent elements was not guaranteed to be preserved	required to be preserved
LWG 2005	C++11	overloads (3,6) were poorly described	improved the description

[edit] See also

emplace (C++11)	constructs element in-place (public member function) [edit]
emplace_hint (C++11)	constructs elements in-place using a hint (public member function) [edit]
inserter	creates a std::insert_iterator of type inferred from the argument (function template) [edit]

@@ Line 1: / Line 1: @@
-{{cpp/container/multimap/title | insert}}
+{{cpp/container/multimap/title|insert}}
 {{cpp/container/multimap/navbar}}
 {{dcl begin}}
-{{dcl | num=1 |
+{{dcl|num=1|
 iterator insert( const value_type& value );
 }}
-{{dcl | num=1 | since=c++17 |
+{{dcl|num=2|since=c++17|
 iterator insert( value_type&& value );
 }}
-{{dcl | num=2 | since=c++11 |
+{{dcl|num=3|since=c++11|
 template< class P >
 iterator insert( P&& value );
 }}
-{{dcl rev begin | num=3}}
+{{dcl rev multi|num=4|until1=c++11
-{{dcl | until=c++11 |
+|dcl1=
-iterator insert( iterator hint, const value_type& value );
+iterator insert( iterator pos, const value_type& value );
+|dcl2=
+iterator insert( const_iterator pos, const value_type& value );
 }}
-{{dcl | since=c++11 |
+{{dcl|num=5|since=c++17|
-iterator insert( const_iterator hint, const value_type& value );
+iterator insert( const_iterator pos, value_type&& value );
 }}
-{{dcl rev end}}
+{{dcl|num=6|since=c++11|
-{{dcl | num=3 | since=c++17 |
-iterator insert( const_iterator hint, value_type&& value );
-}}
-{{dcl | num=4 | since=c++11 |
 template< class P >
-iterator insert( const_iterator hint, P&& value );
+iterator insert( const_iterator pos, P&& value );
 }}
-{{dcl | num=5 |
+{{dcl|num=7|
 template< class InputIt >
 void insert( InputIt first, InputIt last );
 }}
-{{dcl | num=6 | since=c++11 |
+{{dcl|num=8|since=c++11|
 void insert( std::initializer_list<value_type> ilist );
 }}
-{{dcl | num=7 | since=c++17 |
+{{dcl|num=9|since=c++17|
-iterator insert(node_type&& nh);
+iterator insert( node_type&& nh );
 }}
-{{dcl | num=8 | since=c++17 |
+{{dcl|num=10|since=c++17|
-iterator insert(const_iterator hint, node_type&& nh);
+iterator insert( const_iterator pos, node_type&& nh );
 }}
 {{dcl end}}
@@ Line 44: / Line 42: @@
 Inserts element(s) into the container.
-@1-2@ inserts {{tt|value}}. If the container has elements with equivalent key, inserts at the upper bound of that range.{{mark since c++11}} The overload {{v|2}} is equivalent to {{c|emplace(std::forward<P>(value))}} and only participates in overload resolution if {{c|std::is_constructible<value_type, P&&>::value {{==}} true}}.
+@1-3@ Inserts {{c|value}}. If the container has elements with equivalent key, inserts at the upper bound of that range.
+@@ Overload {{v|3}} is equivalent to {{c|emplace(std::forward<P>(value))}} and only participates in overload resolution if {{c|1=std::is_constructible<value_type, P&&>::value == true}}.
-@3-4@ inserts {{tt|value}} in the position as close as possible, just prior{{mark since c++11}}, to {{tt|hint}}. The overload {{v|4}} is equivalent to {{c|emplace_hint(hint, std::forward<P>(value))}} and only participates in overload resolution if {{c|std::is_constructible<value_type, P&&>::value {{==}} true}}.
+@4-6@ Inserts {{c|value}} in the position as close as possible to the position just prior to {{c|pos}}.
+@@ Overload {{v|6}} is equivalent to {{c|emplace_hint(hint, std::forward<P>(value))}} and only participates in overload resolution if {{c|1=std::is_constructible<value_type, P&&>::value == true}}.
-@5@ inserts elements from range {{tt|[first, last)}}.
+@7@ Inserts elements from range {{range|first|last}}.
-@6@ inserts elements from initializer list {{tt|ilist}}.
+@8@ Inserts elements from initializer list {{c|ilist}}.
-{{cpp/container/node_handle_insert_desc|multimap|7|8}}
+{{cpp/container/node_handle insert desc|multimap|9|10}}
+{{cpp/container/note iterator invalidation|multimap|insert}}
-{{cpp/container/note_iterator_invalidation|multimap|insert}}
 ===Parameters===
 {{par begin}}
-{{par | hint | {{rev begin}}{{rev|until=c++11|iterator, used as a suggestion as to where to start the search}}{{rev|since=c++11|iterator to the position before which the new element will be inserted}}{{rev end}}}}
+{{par|pos|iterator to the position before which the new element will be inserted}}
-{{par | value | element value to insert}}
+{{par|value|element value to insert}}
-{{par | first, last | range of elements to insert}}
+{{par|first, last|range of elements to insert}}
-{{par | ilist | initializer list to insert the values from}}
+{{par|ilist|initializer list to insert the values from}}
-{{par | nh | a compatible [[cpp/container/node_handle|node handle]]}}
+{{par|nh|a compatible [[cpp/container/node_handle|node handle]]}}
 {{par hreq}}
-{{par req named | InputIt | InputIterator}}
+{{par req named|InputIt|InputIterator}}
 {{par end}}
 ===Return value===
-@1-4@ Returns an iterator to the inserted element.
+@1-6@ An iterator to the inserted element.
-@5-6@ (none)
+@7,8@ (none)
-{{cpp/container/node_handle_insert_return|multimap|7|8}}
+{{cpp/container/node handle insert return|multimap|9|10}}
 ===Exceptions===
-@1-4@ If an exception is thrown by any operation, the insertion has no effect.
+@1-6@ If an exception is thrown by any operation, the insertion has no effect.
-{{todo|cases 5-6}}
+@7,8@ No exception safety guarantee.
+@9,10@ If an exception is thrown by any operation, the insertion has no effect.
 ===Complexity===
-@1-2@ Logarithmic in the size of the container, {{tt|O(log(size()))}}.
+@1-3@ {{tt|O(log(size()))}}
-{{rev begin}}
+@4-6@ Amortized constant if the insertion happens in the position just before {{c|pos}}, {{tt|O(log(size()))}} otherwise.
-{{rev | until=c++11 |
-@3-4@ Amortized constant if the insertion happens in the position just ''after'' the hint, logarithmic in the size of the container otherwise.
-}}
-{{rev | since=c++11 |
-@3-4@ Amortized constant if the insertion happens in the position just ''before'' the hint, logarithmic in the size of the container otherwise.
-}}
-{{rev end}}
-@5-6@ {{tt|O(N*log(size() + N))}}, where N is the number of elements to insert.
+@7,8@ {{tt|O(N&middot;log(size() + N))}}, where {{tt|N}} is the number of elements to insert.
-@7@ Logarithmic in the size of the container, {{tt|O(log(size()))}}.
+@9@ {{tt|O(log(size()))}}
-@8@ Amortized constant if the insertion happens in the position just ''before'' the hint, logarithmic in the size of the container otherwise.
+@10@ Amortized constant if the insertion happens in the position just before {{c|pos}}, {{tt|O(log(size()))}} otherwise.
 ===Example===
 {{example
-| code=
+|code=
+#include <functional>
 #include <iostream>
-#include <string>
 #include <map>
-#include <functional>
+#include <string>
+#include <string_view>
+#include <utility>
 template<class M>
-void print(const M& mmap)
+void print(const std::string_view rem, const M& mmap)
 {
-     for (auto & e : mmap)
+    std::cout << rem << ' ';
-         std::cout << "{" << e.first << "," << e.second << "} ";
+     for (const auto& e : mmap)
+         std::cout << '{' << e.first << ',' << e.second << "} ";
      std::cout << '\n';
 }
@@ Line 115: / Line 113: @@
 int main()
 {
-  // list-initialize
+    // list-initialize
-  std::multimap<int, std::string, std::greater<int>> mmap
+    std::multimap<int, std::string, std::greater<int>> mmap
-    {{2, "foo"}, {2, "bar"}, {3, "baz"}, {1, "abc"}, {5, "def"}};
+        {{2, "foo"}, {2, "bar"}, {3, "baz"}, {1, "abc"}, {5, "def"}};
+    print("#1", mmap);
-  // insert using value_type
-  mmap.insert(decltype(mmap)::value_type(5, "pqr"));
+    // insert using value_type
-  print(mmap);
+    mmap.insert(decltype(mmap)::value_type(5, "pqr"));
+    print("#2", mmap);
-  // insert using make_pair
-  mmap.insert(std::make_pair(6, "uvw"));
+    // insert using pair
-  print(mmap);
+    mmap.insert(std::pair{6, "uvw"});
+    print("#3", mmap);
-  mmap.insert({7, "xyz"});
-  print(mmap);
+    mmap.insert({7, "xyz"});
+    print("#4", mmap);
-  // insert using initialization_list
-  mmap.insert({{5, "one"}, {5, "two"}});
+    // insert using initializer_list
-  print(mmap);
+    mmap.insert({{5, "one"}, {5, "two"}});
+    print("#5", mmap);
-  // erase all entries with key 5
-  mmap.erase(5);
+    // insert using a pair of iterators
-  print(mmap);
+    mmap.clear();
+    const auto il = {std::pair{1, "ä"}, {2, "ё"}, {2, "ö"}, {3, "ü"}<!---->};
-  // find and erase a specific entry
+    mmap.insert(il.begin(), il.end());
-  auto pos = mmap.begin();
+    print("#6", mmap);
-  while (pos != mmap.end() && pos->second != "bar") ++pos;
-  if(pos != mmap.end() mmap.erase(pos);
-  print(mmap);
 }
-| output=
+|output=
-{5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
+#1 {5,def} {3,baz} {2,foo} {2,bar} {1,abc}
-{6,uvw} {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
+#2 {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
-{7,xyz} {6,uvw} {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
+#3 {6,uvw} {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
-{7,xyz} {6,uvw} {5,def} {5,pqr} {5,one} {5,two} {3,baz} {2,foo} {2,bar} {1,abc}
+#4 {7,xyz} {6,uvw} {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}
-{7,xyz} {6,uvw} {3,baz} {2,foo} {2,bar} {1,abc}
+#5 {7,xyz} {6,uvw} {5,def} {5,pqr} {5,one} {5,two} {3,baz} {2,foo} {2,bar} {1,abc}
-{7,xyz} {6,uvw} {3,baz} {2,foo} {1,abc}
+#6 {3,ü} {2,ё} {2,ö} {1,ä}
 }}
+===Defect reports===
+{{dr list begin}}
+{{dr list item|wg=lwg|dr=233|std=C++98|before={{c|pos}} was just a hint, it could be totally ignored|after=the insertion is required to<br>be as close as possible to the<br>position just prior to {{c|pos}}}}
+{{dr list item|wg=lwg|dr=264|std=C++98|before=the complexity of overload {{v|5}} was required to be linear if<br>the range {{range|first|last}} is sorted according to {{tt|Compare}}|after=removed the linear requirement<br>in this special case}}
+{{dr list item|wg=lwg|dr=371|std=C++98|before=the order of equivalent elements<br>was not guaranteed to be preserved|after=required to be preserved}}
+{{dr list item|wg=lwg|dr=2005|std=C++11|before=overloads {{v|3,6}} were poorly described|after=improved the description}}
+{{dr list end}}
 ===See also===
 {{dsc begin}}
-{{dsc inc | cpp/container/dsc emplace |multimap}}
+{{dsc inc|cpp/container/dsc emplace|multimap}}
-{{dsc inc | cpp/container/dsc emplace_hint |multimap}}
+{{dsc inc|cpp/container/dsc emplace_hint|multimap}}
+{{dsc inc|cpp/iterator/dsc inserter}}
 {{dsc end}}
 {{langlinks|de|es|fr|it|ja|pt|ru|zh}}

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Execution support library (C++26)
Technical specifications
Symbols index
External libraries

Sequence
array (C++11)
vector
vector<bool>
inplace_vector (C++26)
deque
forward_list (C++11)
list
Associative
set
multiset
map
multimap
Unordered associative
unordered_set (C++11)
unordered_multiset (C++11)
unordered_map (C++11)
unordered_multimap (C++11)
Adaptors
stack
queue
priority_queue
flat_set (C++23)
flat_multiset (C++23)
flat_map (C++23)
flat_multimap (C++23)
Views
span (C++20)
mdspan (C++23)
Tables
Iterator invalidation
Member function table
Non-member function table

pos	-	iterator to the position before which the new element will be inserted
value	-	element value to insert
first, last	-	range of elements to insert
ilist	-	initializer list to insert the values from
nh	-	a compatible node handle
Type requirements
- `InputIt` must meet the requirements of LegacyInputIterator.

cppreference.com

Namespaces

Variants

Views

Actions

Difference between revisions of "cpp/container/multimap/insert"

Latest revision as of 13:53, 10 January 2024

Contents

[edit] Parameters

[edit] Return value

[edit] Exceptions

[edit] Complexity

[edit] Example

[edit] Defect reports

[edit] See also

Navigation

Toolbox