# std::basic_string<CharT,Traits,Allocator>::back

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< cpp‎ | string‎ | basic string

| (1) |
CharT& back(); |  | (until C++20)
constexpr CharT& back(); |  | (since C++20)
| (2) |
const CharT& back() const; |  | (until C++20)
constexpr const CharT& back() const; |  | (since C++20)

Returns reference to the last character in the string. The behavior is undefined if empty() is true.

### Parameters

(none)

### Return value

Reference to the last character, equivalent to operator[](size() - 1).

### Complexity

Constant.

### Notes

In libstdc++, `back()` is not available in C++98 mode.

### Example

Run this code

    #include <iostream>
    #include <string>

    int main()
    {
        std::string s("Exemplary");
        char& back1 = s.back();
        back1 = 's';
        std::cout << s << '\n'; // "Exemplars"

        std::string const c("Exemplary");
        char const& back2 = c.back();
        std::cout << back2 << '\n'; // 'y'
    }

Output:

    Exemplars
    y

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 534 | C++98 | std::basic_string did not have the member function `back()` | added

### See also

front (DR*) | accesses the first character (public member function)
back (C++17) | accesses the last character (public member function of `std::basic_string_view<CharT,Traits>`)

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