Difference between revisions of "cpp/concepts/regular"
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The {{tt|regular}} concept specifies that a type is ''regular'', that is, it is copyable, default constructible, and equality comparable. It is satisfied by types that behave similarly to built-in types like {{c|int}}, and that are comparable with {{tt|{{==}}}}. | The {{tt|regular}} concept specifies that a type is ''regular'', that is, it is copyable, default constructible, and equality comparable. It is satisfied by types that behave similarly to built-in types like {{c|int}}, and that are comparable with {{tt|{{==}}}}. | ||
| − | {{ | + | ===Example=== |
| + | {{example|code= | ||
| + | #include <concepts> | ||
| + | #include <iostream> | ||
| − | { | + | template<std::regular T> |
| + | struct Single { | ||
| + | T value; | ||
| + | friend bool operator==(const Single&, const Single&) = default; | ||
| + | }; | ||
| − | + | int main() | |
| − | + | { | |
| − | + | Single<int> myInt1{4}; | |
| − | + | Single<int> myInt2; | |
| − | + | myInt2 = myInt1; | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | if (myInt1 == myInt2) | |
| − | + | std::cout << "Equal\n"; | |
| − | + | ||
| − | + | std::cout << myInt1.value << ' ' << myInt2.value << '\n'; | |
| + | } | ||
| + | |output= | ||
| + | Equal | ||
| + | 4 4 | ||
| + | }} | ||
| + | |||
| + | {{langlinks|ja|zh}} | ||
Revision as of 06:29, 22 September 2019
| Defined in header <concepts>
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| template <class T> concept regular = std::semiregular<T> && std::equality_comparable<T>; |
(since C++20) | |
The regular concept specifies that a type is regular, that is, it is copyable, default constructible, and equality comparable. It is satisfied by types that behave similarly to built-in types like int, and that are comparable with ==.
Example
Run this code
#include <concepts> #include <iostream> template<std::regular T> struct Single { T value; friend bool operator==(const Single&, const Single&) = default; }; int main() { Single<int> myInt1{4}; Single<int> myInt2; myInt2 = myInt1; if (myInt1 == myInt2) std::cout << "Equal\n"; std::cout << myInt1.value << ' ' << myInt2.value << '\n'; }
Output:
Equal 4 4
