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

 

C++

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std::vector

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vector::emplace_back (C++11)

vector::pop_back

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Deduction guides(C++17)

 

void push_back( const T& value );	(1)
void push_back( T&& value );	(2)	(since C++11)

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 the new size() is greater than capacity() then all iterators and references (including the past-the-end iterator) are invalidated. Otherwise only the past-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 also throw std::length_error when push_back causes a reallocation that would exceed max_size, due to implicitly calling an equivalent of reserve(size()+1).

Example

Run this code

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

Output:

vector holds: "abc" "def" 
Moved-from string 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)