std::vector<T,Allocator>::push_back (3) - Linux Manuals

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


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


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.


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



Amortized constant.


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)


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).


// Run this code

  #include <vector>
  #include <iostream>
  #include <iomanip>

  int main()
      std::vector<std::string> numbers;

      std::string s = "def";

      std::cout << "vector holds: ";
      for (auto&& i : numbers) std::cout << std::quoted(i) << ' ';
      std::cout << "\nMoved-from string holds " << std::quoted(s) << '\n';


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

See also

emplace_back constructs an element in-place at the end
             (public member function)
             removes the last element
pop_back (public member function)