C++ Concepts

 C++ Concepts

Concepts are a feature introduced in C++20 that enable more expressive and constrained generic programming. They allow you to define requirements on template parameters, making it easier to write generic code that is more readable and less error-prone. Here's an example that demonstrates the usage of concepts:

#include <iostream>

#include <concepts>

template <typename T>

concept Integral = std::is_integral<T>::value;

template <Integral T>

T multiply(T a, T b) {

    return a * b;

}

int main() {

    int x = 5;

    int y = 10;

    int result = multiply(x, y);

    std::cout << "Result: " << result << std::endl;

    // Won't compile: 'double' is not an integral type

    // double a = 2.5;

    // double b = 3.5;

    // double invalidResult = multiply(a, b);

    return 0;

}

In the above code, we define a concept named Integral using the std::is_integral trait. The Integral concept checks if the template argument is an integral type. We then define a function template multiply that uses the Integral concept as a constraint. This ensures that the function can only be instantiated with integral types.

Inside the main function, we call multiply with two int arguments, which satisfies the Integral concept. We print the result. If we try to call multiply with double arguments, it won't compile due to the constraint of the concept.

Concepts provide a powerful mechanism to express type requirements in templates and improve code clarity and correctness, especially in generic programming scenarios.