1. Introduction

Goal

In this tutorial, we will learn how to dynamically allocate and deallocate memory in C++. We will explore the new and delete operators and understand how to use them effectively to manage memory.

Learning outcomes

By the end of this tutorial, you will be able to:
- Understand dynamic memory allocation and deallocation in C++
- Use new and delete operators efficiently
- Identify and apply best practices for dynamic memory management

Prerequisites

A basic understanding of C++ syntax and programming concepts such as variables, data types, and pointers is required.

2. Step-by-Step Guide

Dynamic Memory Allocation

Dynamic memory allocation is the process of assigning memory during runtime. In C++, we use the new operator to allocate memory dynamically.

Syntax:

pointerVariable = new dataType;

This will allocate memory of size dataType and the address is assigned to the pointerVariable.

Deallocating Memory

To deallocate or free the memory assigned dynamically, we use the delete operator.

Syntax:

delete pointerVariable;

This will free up the memory that was previously allocated to pointerVariable.

Best Practices

1. Always check if the memory is successfully allocated before using it.
2. Always deallocate the memory after use to avoid memory leaks.
3. Be cautious while deallocating memory. Deleting memory that was not dynamically allocated or deleting the same memory twice can lead to undefined behavior.

3. Code Examples

Example 1: Allocating Memory for an Integer

int* ptr = new int;
if(ptr == nullptr) {
    // Memory allocation failed
    cout << "Memory allocation failed\n";
    return 0;
}
*ptr = 5;
cout << "Value: " << *ptr << "\n";
delete ptr; // deallocating memory

Here, we allocate memory for an integer using new. We check if the memory is successfully allocated. If yes, we assign a value to it and print it. Finally, we deallocate the memory using delete.

Expected output:

Value: 5

4. Summary

In this tutorial, we learned about dynamic memory allocation and deallocation in C++. We learned how to use the new and delete operators to manage memory effectively. We also discussed some best practices for memory management.

Next Steps

Now that you know how to manage memory, try to implement it in your projects. You can also learn about memory leaks and how to detect and prevent them.

Additional Resources

• C++ Documentation: new and delete
• C++ Tutorial: Dynamic Memory

5. Practice Exercises

Exercise 1

Write a program to dynamically allocate memory for a float variable, assign a value and print it.

Solution

float* ptr = new float;
if(ptr == nullptr) {
    cout << "Memory allocation failed\n";
    return 0;
}
*ptr = 3.14;
cout << "Value: " << *ptr << "\n";
delete ptr;

This allocates memory for a float, assigns a value of 3.14, and prints it. Finally, it deallocates the memory.

Exercise 2

Write a program to dynamically allocate memory for an array of integers, assign values, and print them.

Solution

int* ptr = new int[5];
if(ptr == nullptr) {
    cout << "Memory allocation failed\n";
    return 0;
}
for(int i=0; i<5; i++) {
    ptr[i] = i+1;
}
for(int i=0; i<5; i++) {
    cout << ptr[i] << " ";
}
delete[] ptr;

This allocates memory for an array of 5 integers, assigns values, and prints them. Finally, it deallocates the memory.

Remember, when deallocating memory allocated for arrays, use delete[] instead of delete.