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

 

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std::deque

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deque::deque deque::~deque deque::operator= deque::assign deque::assign_range (C++23)   deque::get_allocator Element access deque::at deque::operator[] deque::front deque::back Iterators deque::begindeque::cbegin (C++11) deque::enddeque::cend (C++11) deque::rbegindeque::crbegin (C++11) deque::renddeque::crend (C++11)	Capacity deque::empty deque::size deque::max_size deque::shrink_to_fit (DR*) Modifiers deque::clear deque::insert deque::insert_range (C++23) deque::emplace deque::erase deque::push_front deque::emplace_front (C++11) deque::prepend_range (C++23) deque::pop_front deque::push_back deque::emplace_back (C++11) deque::append_range (C++23) deque::pop_back deque::resize deque::swap
Non-member functions
operator==operator<=> (C++20) swap(std::deque) erase(std::deque)erase_if(std::deque) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (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:

T is not CopyInsertable into deque.

(since C++11)

• T is not CopyAssignable.

2) Inserts value before pos, possibly using move semantics.

If any of the following conditions is satisfied, the behavior is undefined:

• T is not MoveInsertable into deque.
• T is not MoveAssignable.

3) Inserts count copies of the value before pos.

If any of the following conditions is satisfied, the behavior is undefined:

T is not CopyInsertable into deque.

(since C++11)

• T is not CopyAssignable.

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:

T is not EmplaceConstructible into deque from *first. T is not MoveInsertable into deque. T does not satisfy the requirements of MoveConstructible, MoveAssignable or Swappable.

(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.

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

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.

Complexity

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

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)

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]

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

See also

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

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