std::vector<T,Allocator>::back
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reference back();
(1)
(constexpr since C++20)
const_reference back() const;
(2)
(constexpr since C++20)
Returns a reference to the last element in the container.
If empty() is true, the behavior is undefined.
(until C++26)If empty() is true:
- If the implementation is hardened, a contract violation occurs. Moreover, if the contract-violation handler returns under "observe" evaluation semantic, the behavior is undefined.
- If the implementation is not hardened, the behavior is undefined.
Contents
[edit] Return value
Reference to the last element.
[edit] Complexity
Constant.
[edit] Notes
For a non-empty container c, the expression c.back() is equivalent to *std::prev (c.end()).
[edit] Example
Run this code
#include <cassert> #include <vector> int main() { std::vector <char> letters{'a', 'b', 'c', 'd'}; assert (letters.back() == 'd'); }