Understanding C++ Array – A Comprehensive Guide

The popular programming language C++ is used for a wide range of projects, including system design, game design, and software development. An array is a group of related data objects placed in close proximity to each other and forms part of the C++ programming language. 

In this blog, we will go through the different aspects of C++ arrays, their features, advantages, etc. We will also cover dynamic C++ arrays and how they are used in C++ programming. 

What is a C++ Array?

An array is a group of contiguous memory locations containing elements of the same data type. In C++, an array can be declared using the following syntax:

data_type array_name[array_size];

Here, data_type is the data type of the array elements, array_name is the name of the array, and array_size is the number of elements in the array.

For example, the following code declares an array named numbers that can hold five integer values:

int numbers[5];

When to Use C++ Array?

These are beneficial when the array’s size is known ahead of time and will not vary during execution. They are also more memory efficient than dynamic arrays because memory allocation occurs during compilation rather than runtime. Because the memory is contiguous and does not need to be searched, they are also quicker in access time.

Features of C++ Array

The following are the features of C++ arrays:

• The size of an array can’t be changed during runtime since it has a set size.

• Sequential access is expedited because array members are placed in adjacent memory slots.

• The final element is indexed by array_size – 1.

• The same data type is a requirement for all of the elements found in an array built with C++.

• Using an index, arrays offer the capability of randomly accessing any element. This means that every element in the array can be obtained.

Advantages of C++ Array

Arrays have several advantages. These include:

• Utilizing the index of an array allows for quick access to its contiguous memory regions where the items are stored.

• Linked lists utilize non-contiguous memory allocation, resulting in lower memory efficiency.

• They are implemented with ease and are frequently utilized in programming.

• Easy integration into larger applications is achievable, thanks to the interoperability of arrays with a wide variety of C++ libraries and APIs.

You can learn more about arrays in C++ through this in-depth C++ course. 

How to Use C++ Arrays?

Arrays in C++ can be used in several ways, including:

Declaring an Array

To declare an array in C++, use the syntax data_type array_name[array_size]. For example,

int numbers[5];

This code declares a dynamic array named numbers that can hold five integer values.

Initializing an Array

To initialize the elements of an array, use the following syntax:

data_type array_name[array_size] = {element_1, element_2, …, element_n};

For example,

int numbers[5] = {10, 20, 30, 40, 50};

Accessing Array Elements

Array elements can be accessed using their index. For example,

int x = numbers[2]; // access the third element (30)

Changing Array Elements

Array elements can be changed using their index. For example,

numbers[2] = 35; // change the third element to 35

Looping Through an Array

To loop through an array, use a for loop. For example,

for(int i = 0; i < 5; i++) {

    cout << numbers[i] << endl;

}

Multidimensional Arrays

Arrays can also be multi-dimensional. To declare a multidimensional array, use the following syntax:

data_type array_name[array_size_

{sub_array_size_1, sub_array_size_2, …, sub_array_size_n}};

For example,

int matrix[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

In this example, the matrix is a 3×3 array that stores integer values.

Array of Pointers

They can also be used to store pointers. For example,

int *numbers[5];

This declares an array of five integer pointers.

Size of Operator

The sizeof operator in C++ can be used to get the size of an array in bytes. For example,

int numbers[5];

cout << sizeof(numbers) << endl; // prints 20 (5 * 4 bytes per integer)

What is a Dynamic C++ Array?

A dynamic C++ array is an array whose size may be allocated dynamically during runtime. This implies that the array’s size may be adjusted to meet the demands of the program. Pointers and memory allocation methods are used to implement these arrays in C++.

When to Use Dynamic C++ Array?

Dynamic arrays are useful when the array’s size is unknown or may change during execution. They are also handy for dealing with vast volumes of data that cannot be held in memory at the same time. They are more versatile than C++ arrays since they may be enlarged as needed. However, because the memory is not contiguous and must be searched, dynamic arrays might be slower in terms of access time.

Features of Dynamic C++ Array

The following characteristics make dynamic arrays stand out:

• They present the opportunity to modify their size as required, providing flexibility during program execution.

• Contiguous memory allocation is not used in dynamic arrays, resulting in their contents potentially being stored in non-contiguous memory locations.

• All components of a dynamic array must have matching data types.

• Random access to elements is possible with these arrays, allowing access to any given element by simply using its index.

Advantages of Dynamic C++ Array

Dynamic C++ arrays have several advantages over static arrays, such as:

• In response to the application’s demands, they are able to change their size, indicating that they can have various sizes.

• They possess the property of memory allocation that sets them apart from static arrays, making them superior in terms of memory efficiency.

• Bigger applications can be effortlessly integrated with dynamic arrays due to their compatibility with a diverse range of C++ libraries and APIs.

How to Use Dynamic C++ Arrays?

Dynamic arrays can be used in several ways, including:

Declaring a Dynamic Array

To declare a dynamic array in C++, you must use pointers and memory allocation functions. For example,

int *numbers = new int[5];

This code declares a dynamic array named numbers that can hold five integer values.

Initializing a Dynamic Array

To initialize the elements of a dynamic array, use the following syntax:

data_type *array_name = new data_type[array_size];

For example,

int *numbers = new int[5]{10, 20, 30, 40, 50};

Accessing Dynamic Array Elements

Dynamic array elements can be accessed using their index. For example,

int x = numbers[2]; // access the third element (30)

Changing Dynamic Array Elements

Dynamic array elements can be changed using their index. For example,

numbers[2] = 35; // change the third element to 35

Looping Through a Dynamic Array

To loop through a dynamic array, use a for loop. For example,

for(int i = 0; i < 5; i++) {

    cout << numbers[i] << endl;

}

Multidimensional Dynamic Arrays

Dynamic arrays can also be multi-dimensional. To declare a multidimensional dynamic array, use the following syntax:

data_type **array_name = new data_type*[array_size_1];

for(int i = 0; i < array_size_1; i++) {

    array_name[i] = new data_type[array_size_2];

}

For example,

int **matrix = new int*[3];

for(int i = 0; i < 3; i++) {

    matrix[i] = new int[3];

}

matrix[0][0] = 1;

matrix[0][1] = 2;

matrix[0][2] = 3;

matrix[1][0] = 4;

matrix[1][1] = 5;

matrix[1][2] = 6;

matrix[2][0] = 7;

matrix[2][1] = 8;

matrix[2][2] = 9;

In this example, a 3×3 matrix is declared and initialized with values.

Deleting a Dynamic Array

To delete a dynamic array, use the following syntax:

delete[] array_name;

For example,

delete[] numbers;

This code deletes the dynamic array named numbers.

It is critical to remember that failing to delete a dynamic array might result in memory leaks, causing the application to crash or slow down over time. So, remember to delete a dynamic array after using it to minimize memory leaks.

Difference Between C++ Array and Dynamic Array

Static Array	Dynamic Array
It is a fixed-size static data structure that cannot be resized during runtime.  Its size is set at the time of declaration and cannot be modified afterward.	It is a data structure that allows for runtime memory allocation and may be expanded as needed.  To avoid memory leaks, it is formed using the ‘new’ operator and must be deleted with the ‘delete’ operator.

Conclusion

C++ arrays are versatile data structures that allow you to store many components of the same data type in adjacent memory regions. They are memory efficient, quick to access, and simple to utilize. They are frequently used in programming because of their constant size and zero-based indexing and are compatible with a wide range of C++ libraries and APIs.