[string.op.plus] (original) (raw)

27 Strings library [strings]

27.4 String classes [string.classes]

27.4.4 Non-member functions [string.nonmembers]

27.4.4.1 operator+ [string.op.plus]

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs,const basic_string<charT, traits, Allocator>& rhs);template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);

Effects: Equivalent to:basic_string<charT, traits, Allocator> r = lhs; r.append(rhs);return r;

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(basic_string<charT, traits, Allocator>&& lhs,const basic_string<charT, traits, Allocator>& rhs);template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(basic_string<charT, traits, Allocator>&& lhs, const charT* rhs);

Effects: Equivalent to:lhs.append(rhs);return std::move(lhs);

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(basic_string<charT, traits, Allocator>&& lhs, basic_string<charT, traits, Allocator>&& rhs);

Effects: Equivalent to:lhs.append(rhs);return std::move(lhs);except that both lhs and rhsare left in valid but unspecified states.

[Note 1:

If lhs and rhs have equal allocators, the implementation can move from either.

— _end note_]

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, basic_string<charT, traits, Allocator>&& rhs);template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const charT* lhs, basic_string<charT, traits, Allocator>&& rhs);

Effects: Equivalent to:rhs.insert(0, lhs);return std::move(rhs);

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs);

Effects: Equivalent to:basic_string<charT, traits, Allocator> r = rhs; r.insert(0, lhs);return r;

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(charT lhs, const basic_string<charT, traits, Allocator>& rhs);

Effects: Equivalent to:basic_string<charT, traits, Allocator> r = rhs; r.insert(r.begin(), lhs);return r;

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(charT lhs, basic_string<charT, traits, Allocator>&& rhs);

Effects: Equivalent to:rhs.insert(rhs.begin(), lhs);return std::move(rhs);

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);

Effects: Equivalent to:basic_string<charT, traits, Allocator> r = lhs; r.push_back(rhs);return r;

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(basic_string<charT, traits, Allocator>&& lhs, charT rhs);

Effects: Equivalent to:lhs.push_back(rhs);return std::move(lhs);

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, type_identity_t<basic_string_view<charT, traits>> rhs);

Equivalent to:basic_string<charT, traits, Allocator> r = lhs; r.append(rhs);return r;

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(basic_string<charT, traits, Allocator>&& lhs, type_identity_t<basic_string_view<charT, traits>> rhs);

Equivalent to:lhs.append(rhs);return std::move(lhs);

template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(type_identity_t<basic_string_view<charT, traits>> lhs,const basic_string<charT, traits, Allocator>& rhs);

Equivalent to:basic_string<charT, traits, Allocator> r = rhs; r.insert(0, lhs);return r;

Equivalent to:rhs.insert(0, lhs);return std::move(rhs);

[Note 2:

Using a specialization of type_identity_t as a parameter type ensures that an object of type basic_string<charT, traits, Allocator>can be concatenated with an object of a type Thaving an implicit conversion tobasic_string_view<charT, traits> ([over.match.oper]).

— _end note_]