C++

Reference

<vector>

vector

public member function
<vector>

std::vector::back

 reference back();const_reference back() const;
Access last element
Returns a reference to the last element in the vector.

Unlike member vector::end, which returns an iterator just past this element, this function returns a direct reference.

Calling this function on an empty container causes undefined behavior.

Parameters

none

Return value

A reference to the last element in the vector.

If the vector object is const-qualified, the function returns a const_reference. Otherwise, it returns a reference.

Member types reference and const_reference are the reference types to the elements of the vector (see member types).

Example

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// vector::back #include <iostream> #include <vector> int main () { std::vector<int> myvector; myvector.push_back(10); while (myvector.back() != 0) { myvector.push_back ( myvector.back() -1 ); } std::cout << "myvector contains:"; for (unsigned i=0; i<myvector.size() ; i++) std::cout << ' ' << myvector[i]; std::cout << '\n'; return 0; }

Output:
myvector contains: 10 9 8 7 6 5 4 3 2 1 0


Complexity

Constant.

Iterator validity

No changes.

Data races

The container is accessed (neither the const nor the non-const versions modify the container).
The reference returned can be used to access or modify elements. Concurrently accessing or modifying different elements is safe.

Exception safety

If the container is not empty, the function never throws exceptions (no-throw guarantee).
Otherwise, it causes undefined behavior.

See also

vector::front
Access first element (public member function)
vector::at
Access element (public member function)
vector::operator[]
Access element (public member function)
vector::push_back
Add element at the end (public member function)
vector::pop_back
Delete last element (public member function)