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std::deque<T,Allocator>::insert

From cppreference.com
< cpp‎ | container‎ | deque

[edit template]
 
C++
 
Containers library
 
std::deque
Member types
Member functions
Non-member functions
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Deduction guides(C++17)
 
iterator insert( const_iterator pos, const T& value );
 (1) (constexpr since C++26)
iterator insert( const_iterator pos, T&& value );
 (2) (since C++11)
(constexpr since C++26)
iterator insert( const_iterator pos,
                 size_type count, const T& value );
 (3) (constexpr since C++26)
template< class InputIt >
iterator insert( const_iterator pos, InputIt first, InputIt last );
 (4) (constexpr since C++26)
iterator insert( const_iterator pos, std::initializer_list<T> ilist );
 (5) (since C++11)
(constexpr since C++26)

Inserts elements at the specified location in the container.

1) Inserts a copy of value before pos.
If any of the following conditions is satisfied, the behavior is undefined:
(since C++11)
2) Inserts value before pos, possibly using move semantics.
If any of the following conditions is satisfied, the behavior is undefined:
3) Inserts count copies of the value before pos.
If any of the following conditions is satisfied, the behavior is undefined:
(since C++11)
4) Inserts elements from range [first, last) before pos.

This overload has the same effect as overload (3) if InputIt is an integral type.

(until C++11)

This overload participates in overload resolution only if InputIt satisfies the requirements of LegacyInputIterator.

(since C++11)
If any of the following conditions is satisfied, the behavior is undefined:
(since C++11)
  • first or last are iterators into *this.
5) Inserts elements from initializer list ilist before pos.
Equivalent to insert(pos, ilist.begin(), ilist.end()).


All iterators (including the end() iterator) are invalidated. References are invalidated too, unless pos == begin() or pos == end(), in which case they are not invalidated.

Contents

[edit] Parameters

pos - iterator before which the content will be inserted
value - element value to insert
count - number of elements to insert
first, last - the pair of iterators defining the range of elements to insert
ilist - std::initializer_list to insert the values from

[edit] Return value

1,2) Iterator pointing to the inserted value.
3-5) Iterator pointing to the first element inserted, or pos if no element is inserted.

[edit] Complexity

Linear in the number of elements inserted plus std::min(std::distance(begin(), pos), std::distance(pos, end())).

[edit] Exceptions

If an exception is thrown other than by

  • the copy constructor of T,
  • the move constructor of T,
(since C++11)
  • the copy assignment operator of T,
  • the move assignment operator of T,
(since C++11)

this function has no effect (strong exception guarantee).

If an exception is thrown when inserting a single element at either end, this function has no effect (strong exception guarantee). Otherwise, if an exception is thrown by the move constructor of a non-CopyInsertable T, the effects are unspecified.

(since C++11)

[edit] Example

Run this code
#include <iostream>
#include <iterator>
#include <string_view>
#include <deque>
 
namespace stq
{
    void println(std::string_view rem, const std::deque<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::deque<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::deque<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]

[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 149 C++98 overloads (3) and (4) returned nothing returns an iterator
LWG 247 C++98 the complexity was only specified
for inserting a single element 		also specified for inserting
multiple elements

[edit] See also

(C++11)
 constructs element in-place
(public member function) [edit]
inserts an element to the beginning
(public member function) [edit]
adds an element to the end
(public member function) [edit]
creates a std::insert_iterator of type inferred from the argument
(function template) [edit]
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