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

 

C++

Compiler support

Freestanding and hosted

Language

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

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Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

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

Views

span (C++20)

 

std::vector

Member functions

vector::vector

vector::~vector

vector::operator=

vector::assign

vector::get_allocator

Element access

vector::at

vector::operator[]

vector::front

vector::back

vector::data

Iterators

vector::beginvector::cbegin (C++11)

vector::endvector::cend (C++11)

vector::rbeginvector::crbegin (C++11)

vector::rendvector::crend (C++11)

Capacity

vector::empty

vector::size

vector::max_size

vector::reserve

vector::capacity

vector::shrink_to_fit (C++11)

Modifiers

vector::clear

vector::insert

vector::emplace (C++11)

vector::erase

vector::push_back

vector::emplace_back (C++11)

vector::pop_back

vector::resize

vector::swap

Non-member functions

std::swap

eraseerase_if (C++20)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Deduction guides(C++17)

 

	(1)
iterator insert( iterator pos, const T& value );			(until C++11)
iterator insert( const_iterator pos, const T& value );			(since C++11) (until C++20)
constexpr iterator insert( const_iterator pos, const T& value );			(since C++20)
		(2)
iterator insert( const_iterator pos, T&& value );				(since C++11) (until C++20)
constexpr iterator insert( const_iterator pos, T&& value );				(since C++20)
			(3)
void insert( iterator pos, size_type count, const T& value );					(until C++11)
iterator insert( const_iterator pos, size_type count, const T& value );					(since C++11) (until C++20)
constexpr iterator insert( const_iterator pos, size_type count,                            const T& value );					(since C++20)
				(4)
template< class InputIt > void insert( iterator pos, InputIt first, InputIt last );						(until C++11)
template< class InputIt > iterator insert( const_iterator pos,                  InputIt first, InputIt last );						(since C++11) (until C++20)
template< class InputIt > constexpr iterator insert( const_iterator pos,                            InputIt first, InputIt last );						(since C++20)
					(5)
iterator insert( const_iterator pos, std::initializer_list<T> ilist );							(since C++11) (until C++20)
constexpr iterator insert( const_iterator pos,                            std::initializer_list<T> ilist );							(since C++20)

Inserts elements at the specified location in the container.

1-2) 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 InputIt is an integral type.	(until C++11)
This overload participates in overload resolution only if InputIt qualifies as LegacyInputIterator, to avoid ambiguity with the overload (3).	(since C++11)

The behavior is undefined if first and last are iterators into *this.

5) inserts elements from initializer list ilist before pos.

Causes reallocation if the new size() is greater than the old capacity(). If the new size() is greater than capacity(), all iterators and references are invalidated. Otherwise, only the iterators and references before the insertion point remain valid. The past-the-end iterator is also invalidated.

Parameters

pos	-	iterator before which the content will be inserted. pos may be the end() iterator
value	-	element value to insert
count	-	number of elements to insert
first, last	-	the range of elements to insert, can't be iterators into container for which insert is called
ilist	-	initializer list to insert the values from
Type requirements
- T must meet the requirements of CopyAssignable and CopyInsertable in order to use overload (1).
- T must meet the requirements of MoveAssignable and MoveInsertable in order to use overload (2).
- T must meet the requirements of CopyAssignable and CopyInsertable in order to use overload (3).
- T must meet the requirements of EmplaceConstructible in order to use overload (4,5).
- T must meet the requirements of MoveAssignable and MoveInsertable in order to use overload (4). required only if InputIt satisfies LegacyInputIterator but not LegacyForwardIterator. (until C++17)
- T must meet the requirements of Swappable, MoveAssignable, MoveConstructible and MoveInsertable in order to use overload (4,5). (since C++17)

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 is empty.

Complexity

1-2) Constant plus linear in the distance between pos and end of the container.

3) Linear in count plus linear in the distance between pos and end of the container.

4) Linear in std::distance(first, last) plus linear in the distance between pos and end of the container.

5) Linear in ilist.size() plus linear in the distance between pos and end of the container.

Exceptions

If an exception is thrown when inserting a single element at the end, and T is CopyInsertable or std::is_nothrow_move_constructible<T>::value is true, there are no effects (strong exception guarantee).

Example

Run this code

#include <iostream>
#include <iterator>
#include <vector>
 
void print(int id, const std::vector<int>& container)
{
    std::cout << id << ". ";
    for (const int x: container) {
         std::cout << x << ' ';
    }
    std::cout << '\n';
}
 
int main ()
{
    std::vector<int> c1(3, 100);
    print(1, c1);
 
    auto it = c1.begin();
    it = c1.insert(it, 200);
    print(2, c1);
 
    c1.insert(it, 2, 300);
    print(3, c1);
 
    // `it` no longer valid, get a new one:
    it = c1.begin();
 
    std::vector<int> c2(2, 400);
    c1.insert(std::next(it, 2), c2.begin(), c2.end());
    print(4, c1);
 
    int arr[] = { 501,502,503 };
    c1.insert(c1.begin(), arr, arr + std::size(arr));
    print(5, c1);
 
    c1.insert(c1.end(), { 601,602,603 } );
    print(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

See also

emplace (C++11)	constructs element in-place (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)