std::expected<T,E>:: operator->, std::expected<T,E>:: operator*
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Primary template
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||
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constexpr
const
T
*
operator
-
>
(
)
const
noexcept
;
|
(1) | (since C++23) |
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constexpr
T
*
operator
-
>
(
)
noexcept
;
|
(2) | (since C++23) |
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constexpr
const
T
&
operator
*
(
)
const
&
noexcept
;
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(3) | (since C++23) |
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constexpr
T
&
operator
*
(
)
&
noexcept
;
|
(4) | (since C++23) |
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constexpr
const
T
&&
operator
*
(
)
const
&&
noexcept
;
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(5) | (since C++23) |
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constexpr
T
&&
operator
*
(
)
&&
noexcept
;
|
(6) | (since C++23) |
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void
partial specialization
|
||
|
constexpr
void
operator
*
(
)
const
noexcept
;
|
(7) | (since C++23) |
Accesses the expected value contained in * this .
If
has_value()
is
false
, the behavior is undefined.
Return value
val
)
val
val
)
Notes
These operators do not check whether the optional represents an expected value! You can do so manually by using
has_value()
or simply
operator bool()
. Alternatively, if checked access is needed,
value()
or
value_or()
may be used.
Example
#include <cassert> #include <expected> #include <iomanip> #include <iostream> #include <string> int main() { using namespace std::string_literals; std::expected<int, std::string> ex1 = 6; assert(*ex1 == 6); *ex1 = 9; assert(*ex1 == 9); // *ex1 = "error"s; // error, ex1 contains an expected value of type int ex1 = std::unexpected("error"s); // *ex1 = 13; // UB, ex1 contains an unexpected value assert(ex1.value_or(42) == 42); std::expected<std::string, bool> ex2 = "Moon"s; std::cout << "ex2: " << std::quoted(*ex2) << ", size: " << ex2->size() << '\n'; // You can "take" the expected value by calling operator* on an std::expected rvalue auto taken = *std::move(ex2); std::cout << "taken " << std::quoted(taken) << "\n" "ex2: " << std::quoted(*ex2) << ", size: " << ex2->size() << '\n'; }
Possible output:
ex2: "Moon", size: 4 taken "Moon" ex2: "", size: 0
See also
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returns the expected value
(public member function) |
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returns the expected value if present, another value otherwise
(public member function) |
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checks whether the object contains an expected value
(public member function) |
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returns the unexpected value
(public member function) |