Gain insights into C++20 Concepts to enhance type safety. Delve into creating compiler-checked criteria for templates and improving error clarity for seamless generic code development.

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clang-gcc.tar.gz

c++20

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This course will walk you through the newest version of C++ 20, C++ Concepts.

You will go through one of the most significant new features in C++20, which is Concepts. Concepts allow you to create compiler-checked criteria for template parameters, revolutionizing the way you think about and develop generic code. You can use them to provide both syntactic and semantic requirements. They also allow you to explicitly express your goal in the type system. If something goes wrong, you'll get a clear error message from the compiler.

While useful, Concepts can be difficult to apply and even confusing sometimes. This course provides you with the knowledge you need to overcome these obstacles and move on to more complex topics.

Let's get started.

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

## Solution

As we saw earlier, this solution is based on Euclid’s algorithm. On **line 7**, we create a concept `Number` and on **line 10** it is required by the function for both the template parameters. As the same concept is required for both template parameters, only floating-point numbers can be passed to the function.

The function  `gcd()` is based on the following observation: if `d` divides `a` and `d` divides `b`, `d` divides `a - b` as well. So, the GCD of `a` and `b` is the same as the GCD of `a - b` and `b`.

- If `a > b`, replace `b` with `a` and call the function itself again.
- Stop if `fabs(b) < 0.001`. The GCD of `a` and `b`, of course, is `a`. If not, go to the next step. Here, `fabs()` is a function in the `cmath` library that returns the absolute value of a number as a float.
- If `a > b`, replace `a` with `a - b`, then go to the first step.
- If `fabs(b) >= 0.001`, replace `a` with `b`, replace `b` with `a - floor(a / b) * b`, and call the function itself again.

# Solution

As we saw earlier, this solution is based on Euclid’s algorithm. On **line 7**, we create a concept `Number` and on **line 10** it is required by the function for both the template parameters. As the same concept is required for both template parameters, only floating-point numbers can be passed to the function.

The function  `gcd()` is based on the following observation: if `d` divides `a` and `d` divides `b`, `d` divides `a - b` as well. So, the GCD of `a` and `b` is the same as the GCD of `a - b` and `b`.

- If `a > b`, replace `b` with `a` and call the function itself again.
- Stop if `fabs(b) < 0.001`. The GCD of `a` and `b`, of course, is `a`. If not, go to the next step. Here, `fabs()` is a function in the `cmath` library that returns the absolute value of a number as a float.
- If `a > b`, replace `a` with `a - b`, then go to the first step.
- If `fabs(b) >= 0.001`, replace `a` with `b`, replace `b` with `a - floor(a / b) * b`, and call the function itself again.

Get an overview of how to find the GCD of two real numbers using the <requires> clause.

Introduction

The Concept Behind C++ Concepts

Four Ways to use Concepts in Functions

C++ Concepts with Classes

Concepts Shipped with the C++ Standard Library

How to Write Your Own C++ Concepts

How to Use C++ Concepts in Real Life

Summary

Solution: GCD of Two Real Numbers Using the Trailing <requires> c

Solution