23 Strings library [strings]

23.4 String classes [string.classes]

23.4.4 Non-member functions [string.nonmembers]

23.4.4.1 operator+ [string.op.plus]

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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);
1
#
Effects: Equivalent to: basic_string<charT, traits, Allocator> r = lhs; r.append(rhs); return r;
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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);
2
#
Effects: Equivalent to: lhs.append(rhs); return std::move(lhs);
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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);
3
#
Effects: Equivalent to: lhs.append(rhs); return std::move(lhs); except that both lhs and rhs are left in valid but unspecified states.
[Note 1: 
If lhs and rhs have equal allocators, the implementation can move from either.
— end note]
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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);
4
#
Effects: Equivalent to: rhs.insert(0, lhs); return std::move(rhs);
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template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs);
5
#
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);
6
#
Effects: Equivalent to: basic_string<charT, traits, Allocator> r = rhs; r.insert(r.begin(), lhs); return r;
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template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(charT lhs, basic_string<charT, traits, Allocator>&& rhs);
7
#
Effects: Equivalent to: rhs.insert(rhs.begin(), lhs); return std::move(rhs);
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template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);
8
#
Effects: Equivalent to: basic_string<charT, traits, Allocator> r = lhs; r.push_back(rhs); return r;
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template<class charT, class traits, class Allocator> constexpr basic_string<charT, traits, Allocator> operator+(basic_string<charT, traits, Allocator>&& lhs, charT rhs);
9
#
Effects: Equivalent to: lhs.push_back(rhs); return std::move(lhs);
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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);
10
#
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);
11
#
Equivalent to: lhs.append(rhs); return std::move(lhs);
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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);
12
#
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+(type_identity_t<basic_string_view<charT, traits>> lhs, basic_string<charT, traits, Allocator>&& rhs);
13
#
Equivalent to: rhs.insert(0, lhs); return std::move(rhs);
14
#
[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 T having an implicit conversion to basic_string_view<charT, traits> ([over.match.oper]).
— end note]