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.

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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

## Introduction
Should we declare a member function as `const` whenever possible?


Yes, we should! It clarifies design intent, improves readability, and allows the compiler to catch more errors. We might even benefit from some optimizations sometimes.


## `const` Functions
First of all, what is a `const` function?

A `const` member function can not modify any member variables and cannot call any non-`const` functions.  On the other hand, `const` functions can interact with static member variables and functions in a number of ways.

Let’s examine the previous sentence.

* Only member functions can be `const`. As function constness is related to the lack of interaction with the member variables, there is no point in functions that are non-members. 
* A `const` function cannot modify any class members, and it cannot call other non-`const` member functions. Otherwise, the compiler will give an error.

### Non-const member functions

Non-`const` member functions cannot be called from `const` functions.



# Introduction
Should we declare a member function as `const` whenever possible?


Yes, we should! It clarifies design intent, improves readability, and allows the compiler to catch more errors. We might even benefit from some optimizations sometimes.


# `const` Functions
First of all, what is a `const` function?

A `const` member function can not modify any member variables and cannot call any non-`const` functions.  On the other hand, `const` functions can interact with static member variables and functions in a number of ways.

Let’s examine the previous sentence.

* Only member functions can be `const`. As function constness is related to the lack of interaction with the member variables, there is no point in functions that are non-members. 
* A `const` function cannot modify any class members, and it cannot call other non-`const` member functions. Otherwise, the compiler will give an error.

## Non-const member functions

Non-`const` member functions cannot be called from `const` functions.



Let’s learn about const functions and their characteristics.


Introduction

Arguments using const

Local Variables

Local Members

Functions

Return Types

const Parameters

const and Smart Pointers

Rvalue References

Summary

const Functions

Introduction

`const` Functions