C++ Concepts: Improve Type Safety with C++ 20/

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The <requires> Clause

The <requires> Clause

Get an overview of the <requires> clause.

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How to write aq requires clause?

In the first way, we use the required clause between the template parameter list and the function return type, which is auto in this case.

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#include <concepts>
template <typename T>
concept Number = std::integral<T> || std::floating_point<T>;
template <typename T>
requires Number<T>
auto add(T a, T b) {
  return a+b;
}

Note how we use the concept and define our constraint in the requires clause that any T template parameter must satisfy the requirements of the concept Number. In order to determine the return type we ...