[vector.modifiers]

# 23 Containers library [[containers]](./#containers)

## 23.3 Sequence containers [[sequences]](sequences#vector.modifiers)

### 23.3.13 Class template vector [[vector]](vector#modifiers)

#### 23.3.13.5 Modifiers [vector.modifiers]

[🔗](#lib:insert,vector)

`constexpr iterator insert(const_iterator position, const T& x);
constexpr iterator insert(const_iterator position, T&& x);
constexpr iterator insert(const_iterator position, size_type n, const T& x);
template<class InputIterator>
  constexpr iterator insert(const_iterator position, InputIterator first, InputIterator last);
template<[container-compatible-range](container.intro.reqmts#concept:container-compatible-range "23.2.2.1 Introduction [container.intro.reqmts]")<T> R>
  constexpr iterator insert_range(const_iterator position, R&& rg);
constexpr iterator insert(const_iterator position, initializer_list<T>);

template<class... Args> constexpr reference emplace_back(Args&&... args);
template<class... Args> constexpr iterator emplace(const_iterator position, Args&&... args);
constexpr void push_back(const T& x);
constexpr void push_back(T&& x);
template<[container-compatible-range](container.intro.reqmts#concept:container-compatible-range "23.2.2.1 Introduction [container.intro.reqmts]")<T> R>
  constexpr void append_range(R&& rg);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L10328)

*Complexity*: If reallocation happens,
linear in the number of elements of the resulting vector;
otherwise,
linear in the number of elements inserted plus the distance
to the end of the vector[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L10336)

*Remarks*: Causes reallocation if the new size is greater than the old capacity[.](#2.sentence-1)

Reallocation invalidates all the references, pointers, and iterators
referring to the elements in the sequence, as well as the past-the-end iterator[.](#2.sentence-2)

If no reallocation happens, then
references, pointers, and iterators
before the insertion point remain valid
but those at or after the insertion point,
including the past-the-end iterator,
are invalidated[.](#2.sentence-3)

If an exception is thrown other than by
the copy constructor, move constructor,
assignment operator, or move assignment operator ofT or by any InputIterator operation,
there are no effects[.](#2.sentence-4)

If an exception is thrown while inserting a single element at the end andT is *Cpp17CopyInsertable* or is_nothrow_move_constructible_v<T> is true, there are no effects[.](#2.sentence-5)

Otherwise, if an exception is thrown by the move constructor of a non-*Cpp17CopyInsertable*T, the effects are unspecified[.](#2.sentence-6)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L10358)

For the declarations taking a range R,
performs at most one reallocation if:

- [(3.1)](#3.1)

R models ranges​::​[approximately_sized_range](range.approximately.sized#concept:approximately_sized_range "25.4.3 Approximately sized ranges [range.approximately.sized]") andranges​::​distance(rg) <= ranges​::​reserve_hint(rg) is true, or

- [(3.2)](#3.2)

R models ranges​::​[forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]") andR does not model ranges​::​[approximately_sized_range](range.approximately.sized#concept:approximately_sized_range "25.4.3 Approximately sized ranges [range.approximately.sized]")[.](#3.sentence-1)

For the declarations taking a pair of InputIterator,
performs at most one reallocation ifInputIterator meets the *Cpp17ForwardIterator* requirements[.](#3.sentence-2)

[🔗](#lib:erase,vector)

`constexpr iterator erase(const_iterator position);
constexpr iterator erase(const_iterator first, const_iterator last);
constexpr void pop_back();
`

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L10382)

*Effects*: Invalidates iterators and references at or after the point of the erase[.](#4.sentence-1)

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L10386)

*Throws*: Nothing unless an exception is thrown by the
assignment operator or move assignment operator ofT[.](#5.sentence-1)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L10392)

*Complexity*: The destructor of T is called the number of times equal to the
number of the elements erased, but the assignment operator
of T is called the number of times equal to the number of
elements in the vector after the erased elements[.](#6.sentence-1)