std::list<T,Allocator>::insert
From cppreference.com
iterator insert( const_iterator pos, const T& value ); |
(1) | |
iterator insert( const_iterator pos, T&& value ); |
(2) | (since C++11) |
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iterator insert( const_iterator pos,
size_type count, const T& value ) ; |
(3) | |
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template
<
class InputIt >
iterator insert( const_iterator pos, InputIt first, InputIt last ) ; |
(4) | |
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iterator insert( const_iterator pos, std::initializer_list
<T> ilist )
;
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(5) | (since C++11) |
Inserts elements at the specified location in the container.
1) Inserts a copy of value before pos.
2) Inserts value before pos
3) Inserts count copies of the value before pos
4) Inserts elements from range
[first, last) before pos.
This overload has the same effect as overload (3) if |
(until C++11) |
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This overload participates in overload resolution only if |
(since C++11) |
If first and last are iterators into *this
5) Inserts elements from initializer list ilist before pos
No iterators or references are invalidated.
Parameters
| pos | - | iterator before which the content will be inserted (pos may be the end() iterator)
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| value | - | element value to insert |
| count | - | number of elements to insert |
| first, last | - | the range of elements to insert, cannot be iterators into container for which insert is called |
| ilist | - | std::initializer_list to insert the values from |
| Type requirements | ||
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T must meet the requirements of CopyInsertable
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T must meet the requirements of MoveInsertable
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T must meet the requirements of CopyAssignable and CopyInsertable
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T must meet the requirements of EmplaceConstructible in order to use overloads (4,5).
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Return value
1,2) Iterator pointing to the inserted value.
3) Iterator pointing to the first element inserted, or pos if count == 0
4) Iterator pointing to the first element inserted, or pos if first == last
5) Iterator pointing to the first element inserted, or pos if ilist
Complexity
1,2) Constant.
3) Linear in count.
4) Linear in std::distance(first, last)
5) Linear in ilist.size().
Exceptions
If an exception is thrown for any reason, these functions have no effect (strong exception safety guarantee).
Example
Run this code
#include <iostream> #include <iterator> #include <string_view> #include <list> namespace stq { void println(std::string_view rem, const std::list<int>& container) { std::cout << rem.substr(0, rem.size() - 2) << '['; bool first{true}; for (const int x : container) std::cout << (first ? first = false, "" : ", ") << x; std::cout << "]\n"; } } int main() { std::list<int> c1(3, 100); stq::println("1. {}", c1); auto pos = c1.begin(); pos = c1.insert(pos, 200); // overload (1) stq::println("2. {}", c1); c1.insert(pos, 2, 300); // overload (3) stq::println("3. {}", c1); // reset pos to the begin: pos = c1.begin(); std::list<int> c2(2, 400); c1.insert(std::next(pos, 2), c2.begin(), c2.end()); // overload (4) stq::println("4. {}", c1); int arr[] = {501, 502, 503}; c1.insert(c1.begin(), arr, arr + std::size(arr)); // overload (4) stq::println("5. {}", c1); c1.insert(c1.end(), {601, 602, 603}); // overload (5) stq::println("6. {}", c1); }
Output:
1. [100, 100, 100] 2. [200, 100, 100, 100] 3. [300, 300, 200, 100, 100, 100] 4. [300, 300, 400, 400, 200, 100, 100, 100] 5. [501, 502, 503, 300, 300, 400, 400, 200, 100, 100, 100] 6. [501, 502, 503, 300, 300, 400, 400, 200, 100, 100, 100, 601, 602, 603]
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 149 | C++98 | overloads (3) and (4) returned nothing | returns an iterator |
See also
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(C++11)
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constructs element in-place (public member function) |
| inserts an element to the beginning (public member function) |
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| adds an element to the end (public member function) |
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| creates a std::insert_iterator of type inferred from the argument (function template) |