Gain insights into the C++ keyword 'const,' its usage in various contexts, and implications when returning pointers and references. Learn about preventing accidental data changes.

How to use const in C++ by Sándor Dargo_468 x 60 copy.png

In this course, you will learn about the C++ keyword const and its behaviour under different usage conditions, including local, global and static contexts. This course will help you to understand const and its implications when you attempt to return pointers and references in C++. By the end of the course, you will have a solid grip on const and its usage in preventing any accidental change of data.

Secure Coding Practices in C++: A Deep Dive into const

# What is a smart pointer? 
An instance of a smart pointer is an object consisting of a raw pointer and some data for lifetime management. The exact internal representation is not important in our case.

In other words, having a smart pointer means that we have a wrapper object around a pointer, and the general principle for class type parameters kicks in. What’s that general principle?

We should pass around class type parameters by reference, preferably by `const` reference.

We found that passing smart pointers by reference is the result of syntactic difficulties and a lack of understanding in most cases.

The purpose of a smart pointer is proper lifetime management without the need for calling `delete` manually.

When we pass a smart pointer by (`const`) reference, we don’t pass around the shared ownership. In other words, we don’t deal with ownership at all. In this case, there is no need for smart pointers.
If you don't need smart pointers and passing ownership, you should pass around a raw pointer. It will be faster and more readable.

And it will also be faster because you deal directly with the memory address of the pointed value; you don't have to pass through the layer(s) of a smart pointer.

# Types of smart pointers

There are three types of smart pointers in C++. There is no problem with `std::weak_ptr` in general. It’s not used widely and is therefore considered niche. On the other hand, `unique_ptr` is often misused. It’s just passed around by `const` reference because many are unaware of its usage, and to read lengthy C++ error messages.

When a function creates a `unique_ptr` and returns it, we don’t face any problem.

Learn the relationship between const and smart pointers as objects.

Introduction

Arguments using const

Local Variables

Local Members

Functions

Return Types

const Parameters

const and Smart Pointers

Rvalue References

Summary

Smart Pointers as Objects

What is a smart pointer?