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

 

C++

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)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

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)

Iterator invalidation

Member function table

Non-member function table

 

std::vector

Member types

Member functions

vector::vector

vector::~vector

vector::operator=

vector::assign

vector::assign_range (C++23)

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 (DR*)

Modifiers

vector::clear

vector::insert

vector::emplace (C++11)

vector::insert_range (C++23)

vector::erase

vector::push_back

vector::emplace_back (C++11)

vector::append_range (C++23)

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)
void push_back( const T& value );			(until C++20)
constexpr void push_back( const T& value );			(since C++20)
		(2)
void push_back( T&& value );				(since C++11) (until C++20)
constexpr void push_back( T&& value );				(since C++20)

Appends the given element value to the end of the container.

1) The new element is initialized as a copy of value.

2) value is moved into the new element.

If new size() is greater than capacity() the function causes reallocation, in which case all iterators (including the end() iterator) and references to the elements are invalidated. Otherwise only the end() iterator is invalidated.

Parameters

value	-	the value of the element to append
Type requirements
- T must meet the requirements of CopyInsertable in order to use overload (1).
- T must meet the requirements of MoveInsertable in order to use overload (2).

Return value

(none)

Complexity

Amortized constant.

Exceptions

If an exception is thrown (which can be due to Allocator::allocate() or element copy/move constructor/assignment), this function has no effect (strong exception guarantee).

If T's move constructor is not noexcept and T is not CopyInsertable into *this, vector will use the throwing move constructor. If it throws, the guarantee is waived and the effects are unspecified.

(since C++11)

Notes

Some implementations throw std::length_error when push_back causes a reallocation that exceeds max_size (due to an implicit call to an equivalent of reserve(size() + 1)).

Example

Run this code

#include <iomanip>
#include <iostream>
#include <string>
#include <vector>
 
int main()
{
    std::vector<std::string> letters;
 
    letters.push_back("abc");
    std::string s{"def"};
    letters.push_back(std::move(s));
 
    std::cout << "std::vector letters holds: ";
    for (auto&& e : letters)
        std::cout << std::quoted(e) << ' ';
 
    std::cout << "\nMoved-from string s holds: " << std::quoted(s) << '\n';
}

Possible output:

std::vector letters holds: "abc" "def"
Moved-from string s holds: ""

See also

emplace_back (C++11)	constructs an element in-place at the end (public member function)
pop_back	removes the last element (public member function)
back_inserter	creates a std::back_insert_iterator of type inferred from the argument (function template)