21 Strings library [strings]

21.3 String classes [string.classes]

21.3.3 Non-member functions [string.nonmembers]

21.3.3.1 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 rhs are left in valid but unspecified states.
[Note
:
If lhs and rhs have equal allocators, the implementation may 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);