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

(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

#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

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

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