What is the negation (std::negation) metafunction in C++?

Metaprogramming is another great feature of modern C++ that allows programs to redesign themselves during compilation or run time. In C++17, another new feature of metaprogramming is introduced, logical operation metafunctions. These are variadic metafunctions that are conjunction, disjunction, and negation which can be used for metaprogramming features of applications. In this post, we explain what the negation (std::negation) metafunction is.

What are the logical operation metafunctions in C++?

Modern C++ has metaprogramming abilities which is a programming technique that means a program can be compiled to read, create, analyze, or transfer other program code; or it can compile itself. Metaprogramming can change the way code behaves while running.

In C++17, new variadic metafunctions are released for metaprogramming, these are conjunction, conjunction_v, disjunction, disjunction_v, and negation, negation_v. These traits short-circuit in the metaprogramming sense: template specializations that are not required to determine the result are not instantiated.

What is the negation (std::negation) metafunction in C++?

In C++, negation (std::negation) or negation_v (std::negation_v) is a type trait that is defined in the <type_traits> header that is used to design the logical negation between classes (data types, structs, classes). It is a kind of logical template of NOT on a variadic pack of values.

Here is the simple definition of std::conjunction.

Is there a simple example of how to use negation in C++?

Here is a simple example about negation in C++.

Is there a full example of how to use negation in C++?

Here is a full example about negation in C++.

For more new details about std::set, you can check this paper P0013R1

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