operator==, !=, <, <=, >, >=(std::variant)
Defined in header <variant>
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template <class... Types> constexpr bool operator==(const std::variant<Types...>& v, const std::variant<Types...>& w); |
(1) | (since C++17) |
template <class... Types> constexpr bool operator!=(const std::variant<Types...>& v, const std::variant<Types...>& w); |
(2) | (since C++17) |
template <class... Types> constexpr bool operator<(const std::variant<Types...>& v, const std::variant<Types...>& w); |
(3) | (since C++17) |
template <class... Types> constexpr bool operator>(const std::variant<Types...>& v, const std::variant<Types...>& w); |
(4) | (since C++17) |
template <class... Types> constexpr bool operator<=(const std::variant<Types...>& v, const std::variant<Types...>& w); |
(5) | (since C++17) |
template <class... Types> constexpr bool operator>=(const std::variant<Types...>& v, const std::variant<Types...>& w); |
(6) | (since C++17) |
1) Equality operator for variants:
- If v.index() != w.index(), returns
false
; - otherwise if v.valueless_by_exception(), returns
true
; - otherwise returns std::get<v.index()>(v) == std::get<v.index()>(w). The behavior is undefined if std::get<i>(v) == std::get<i>(w) is not a valid expression returning a type convertible to bool, for any
i
.
2) Inequality operator for variants:
- If v.index() != w.index(), returns
true
; - otherwise if v.valueless_by_exception(), returns
false
; - otherwise returns std::get<v.index()>(v) != std::get<v.index()>(w). The behavior is undefined if std::get<i>(v) != std::get<i>(w) is not a valid expression returning a type convertible to bool, for any
i
.
3) Less-than operator for variants:
- If w.valueless_by_exception(), returns
false
; - otherwise if v.valueless_by_exception(), returns
true
; - otherwise if v.index() < w.index(), returns
true
; - otherwise if v.index() > w.index(), returns
false
; - otherwise returns std::get<v.index()>(v) < std::get<v.index()>(w). The behavior is undefined if std::get<i>(v) < std::get<i>(w) is not a valid expression returning a type convertible to bool, for any
i
.
4) Greater-than operator for variants:
- If v.valueless_by_exception(), returns
false
; - otherwise if w.valueless_by_exception(), returns
true
; - otherwise if v.index() > w.index(), returns
true
; - otherwise if v.index() < w.index(), returns
false
; - otherwise returns std::get<v.index()>(v) > std::get<v.index()>(w). The behavior is undefined if std::get<i>(v) > std::get<i>(w) is not a valid expression returning a type convertible to bool, for any
i
.
5) Less-equal operator for variants:
- If v.valueless_by_exception(), returns
true
; - otherwise if w.valueless_by_exception(), returns
false
; - otherwise if v.index() < w.index(), returns
true
; - otherwise if v.index() > w.index(), returns
false
; - otherwise returns std::get<v.index()>(v) <= std::get<v.index()>(w). The behavior is undefined if std::get<i>(v) <= std::get<i>(w) is not a valid expression returning a type convertible to bool, for any
i
.
6) Greater-equal operator for variants:
- If w.valueless_by_exception(), returns
true
; - otherwise if v.valueless_by_exception(), returns
false
; - otherwise if v.index() > w.index(), returns
true
; - otherwise if v.index() < w.index(), returns
false
; - otherwise std::get<v.index()>(v) >= std::get<v.index()>(w). The behavior is undefined if std::get<i>(v) >= std::get<i>(w) is not a valid expression returning a type convertible to bool, for any
i
.
Parameters
v,w | - | variants to compare |
Return value
The boolean result of the comparison as described above.
Example
This section is incomplete Reason: no example |
See also
compares optional objects (function template) |