constexpr basic_string& append(const basic_string& str);

Effects: Equivalent to: return append(str.data(), str.size());

constexpr basic_string& append(const basic_string& str, size_type pos, size_type n = npos);

Effects: Equivalent to: return append(basic_string_view<charT, traits>(str).substr(pos, n));

template<class T> constexpr basic_string& append(const T& t);

Constraints:

• is_convertible_v<const T&, basic_string_view<charT, traits>> is true and
• is_convertible_v<const T&, const charT*> is false.

Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return append(sv.data(), sv.size());

template<class T> constexpr basic_string& append(const T& t, size_type pos, size_type n = npos);

Constraints:

• is_convertible_v<const T&, basic_string_view<charT, traits>> is true and
• is_convertible_v<const T&, const charT*> is false.

Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return append(sv.substr(pos, n));

constexpr basic_string& append(const charT* s, size_type n);

Preconditions: [s, s + n) is a valid range.

Effects: Appends a copy of the range [s, s + n) to the string.

constexpr basic_string& append(const charT* s);

Effects: Equivalent to: return append(s, traits​::​length(s));

constexpr basic_string& append(size_type n, charT c);

Effects: Appends n copies of c to the string.

template<class InputIterator> constexpr basic_string& append(InputIterator first, InputIterator last);

Constraints: InputIterator is a type that qualifies as an input iterator ([container.reqmts]).

Effects: Equivalent to: return append(basic_string(first, last, get_allocator()));

Effects: Equivalent to: return append(basic_string(from_range, std​::​forward<R>(rg), get_allocator()));

constexpr basic_string& append(initializer_list<charT> il);

Effects: Equivalent to: return append(il.data(), il.size());

constexpr void push_back(charT c);

Effects: Equivalent to append(size_type{1}, c).