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operator==,!=,<,<=,>,>=,<=>(std::basic_string_view)

From cppreference.com
 
C++
 
Strings library
 
std::basic_string_view
 
Defined in header <string_view>
(1)
template< class CharT, class Traits >

constexpr bool operator==( std::basic_string_view<CharT,Traits> lhs,

                           std::basic_string_view<CharT,Traits> rhs ) noexcept;
 (since C++17)
(until C++20)
template< class CharT, class Traits >

constexpr bool operator==(
    std::basic_string_view<CharT,Traits> lhs,

    std::type_identity_t<std::basic_string_view<CharT,Traits>> rhs ) noexcept;
 (since C++20)
template< class CharT, class Traits >

constexpr bool operator!=( std::basic_string_view<CharT,Traits> lhs,

                           std::basic_string_view<CharT,Traits> rhs ) noexcept;
 (2) (since C++17)
(until C++20)
template< class CharT, class Traits >

constexpr bool operator<( std::basic_string_view<CharT,Traits> lhs,

                          std::basic_string_view<CharT,Traits> rhs ) noexcept;
 (3) (since C++17)
(until C++20)
template< class CharT, class Traits >

constexpr bool operator<=( std::basic_string_view<CharT,Traits> lhs,

                           std::basic_string_view<CharT,Traits> rhs ) noexcept;
 (4) (since C++17)
(until C++20)
template< class CharT, class Traits >

constexpr bool operator>( std::basic_string_view<CharT,Traits> lhs,

                          std::basic_string_view<CharT,Traits> rhs ) noexcept;
 (5) (since C++17)
(until C++20)
template< class CharT, class Traits >

constexpr bool operator>=( std::basic_string_view<CharT,Traits> lhs,

                           std::basic_string_view<CharT,Traits> rhs ) noexcept;
 (6) (since C++17)
(until C++20)
template< class CharT, class Traits >

constexpr /*comp-cat*/ operator<=>(
    std::basic_string_view<CharT,Traits> lhs,

    std::type_identity_t<std::basic_string_view<CharT,Traits>> rhs ) noexcept;
 (7) (since C++20)

Compares two views.

All comparisons are done via the compare() member function (which itself is defined in terms of Traits::compare()):

  • Two views are equal if both the size of lhs and rhs are equal and each character in lhs has an equivalent character in rhs at the same position.
  • The ordering comparisons are done lexicographically – the comparison is performed by a function equivalent to std::lexicographical_compare.

The implementation provides sufficient additional constexpr and noexcept overloads of these functions so that a basic_string_view<CharT,Traits> object sv may be compared to another object t with an implicit conversion to basic_string_view<CharT,Traits>, with semantics identical to comparing sv and basic_string_view<CharT,Traits>(t).

(until C++20)

The return type of three-way comparison operators (/*comp-cat*/) is Traits::comparison_category if that qualified-id denotes a type, std::weak_ordering otherwise. If /*comp-cat*/ is not a comparison category type, the program is ill-formed.

The <, <=, >, >=, and != operators are synthesized from operator<=> and operator== respectively.

(since C++20)

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