C++ Arrays

Suppose you want to store the marks of five students. You could create five different variables:

int mark1 = 80;
int mark2 = 75;
int mark3 = 90;
int mark4 = 85;
int mark5 = 70;

This works, but it becomes difficult to manage when you have many values.

C++ arrays store multiple values of the same data type in one variable.

What is an Array?

An array is a collection of multiple values of the same data type stored under one name.

For example:

int marks[5] = {80, 75, 90, 85, 70};

Here:

• int is the data type.
• marks is the array name.
• [5] means the array can store 5 values.
• The numbers inside { } are the values.

Creating an Array

The basic syntax is:

dataType arrayName[size];

For example:

int numbers[5];

This creates an integer array that can store 5 values.

You can also give values when creating the array:

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

Accessing Array Elements

Array elements are accessed using an index.

An important rule is that array indexing starts from 0, not 1.

For example:

Index:    0   1   2   3   4
Value:   10  20  30  40  50

So:

numbers[0]

contains 10, while:

numbers[4]

contains 50.

Example:

#include <iostream>
using namespace std;

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

    cout << numbers[0] << "\n";
    cout << numbers[2] << "\n";
    cout << numbers[4];

    return 0;
}

Output:

10
30
50

Changing an Array Element

You can change the value of a particular element using its index.

#include <iostream>
using namespace std;

int main() {
    int numbers[3] = {10, 20, 30};

    numbers[1] = 50;

    cout << numbers[1];

    return 0;
}

Output:

50

The value at index 1 was originally 20, but we changed it to 50.

Looping Through an Array

Loops make it easy to access every element of an array.

#include <iostream>
using namespace std;

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

    for (int i = 0; i < 5; i++) {
        cout << numbers[i] << "\n";
    }

    return 0;
}

Output:

10
20
30
40
50

The loop starts from index 0 and continues until index 4.

Taking Array Input

You can also ask the user to enter the values.

#include <iostream>
using namespace std;

int main() {
    int numbers[5];

    cout << "Enter 5 numbers:\n";

    for (int i = 0; i < 5; i++) {
        cin >> numbers[i];
    }

    cout << "You entered:\n";

    for (int i = 0; i < 5; i++) {
        cout << numbers[i] << "\n";
    }

    return 0;
}

Example input:

10
20
30
40
50

Output:

You entered:
10
20
30
40
50

Finding the Sum of Array Elements

Arrays become especially useful when combined with calculations.

#include <iostream>
using namespace std;

int main() {
    int numbers[5] = {10, 20, 30, 40, 50};
    int sum = 0;

    for (int i = 0; i < 5; i++) {
        sum += numbers[i];
    }

    cout << "Sum: " << sum;

    return 0;
}

Output:

Sum: 150

The loop visits each element and adds it to sum.

Multidimensional Arrays

C++ also allows you to create arrays with more than one dimension.

A two-dimensional array can be used to store data in rows and columns.

For example:

#include <iostream>
using namespace std;

int main() {
    int numbers[2][3] = {
        {10, 20, 30},
        {40, 50, 60}
    };

    cout << numbers[0][1] << "\n";
    cout << numbers[1][2];

    return 0;
}

Output:

20
60

Two-dimensional arrays are useful for tables, grids, and similar data.

A Simple Example

Let’s create a program to find the largest number in an array.

#include <iostream>
using namespace std;

int main() {
    int numbers[5] = {25, 10, 45, 30, 15};
    int largest = numbers[0];

    for (int i = 1; i < 5; i++) {
        if (numbers[i] > largest) {
            largest = numbers[i];
        }
    }

    cout << "Largest number: " << largest;

    return 0;
}

Output:

Largest number: 45

Key Points to Remember

• An array stores multiple values of the same data type.
• Array indexing starts from 0.
• The first element is at index 0.
• You can access an element using its index.
• Loops are useful for working with arrays.
• Arrays can have one or more dimensions.
• The size of a basic array is fixed when it is created.

Mini Quiz

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C++ PROGRAMMING - QUIZ 8

1 / 5

Q1. Which of the following correctly creates an array that can store 5 integers?

int numbers[5];

int numbers(5);

array numbers[5];

int numbers;

2 / 5

Q2. What is the index of the first element in a C++ array?

0

1

-1

5

3 / 5

Q3. What value is stored in numbers[2]?

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

10

20

30

40

4 / 5

Q4. What is the output of the following program?

#include <iostream>
using namespace std;

int main() {
int numbers[3] = {10, 20, 30};
numbers[1] = 50;

cout << numbers[1];

return 0;
}

20

30

40

50

5 / 5

Q5. What is the output of the following program?

#include
using namespace std;

int main() {
int numbers[5] = {10, 20, 30, 40, 50};
int sum = 0;

for (int i = 0; i < 5; i++) {
sum += numbers[i];
}

cout << sum;

return 0;
}

100

120

150

200

Your score is

The average score is 0%

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By Wordpress Quiz plugin

#include <iostream>
using namespace std;

int main() {
    int marks[5] = {80, 75, 90, 85, 70};
    int total = 0;
    int highest = marks[0];

    cout << "Student Marks:\n";

    for (int i = 0; i < 5; i++) {
        cout << marks[i] << "\n";
        total += marks[i];

        if (marks[i] > highest) {
            highest = marks[i];
        }
    }

    double average = total / 5.0;

    cout << "\nTotal: " << total << "\n";
    cout << "Average: " << average << "\n";
    cout << "Highest Mark: " << highest;

    return 0;
}

What’s Next?

In the next chapter, we will learn about C++ Strings and see how to work with names, sentences, and other text in C++.

Frequently Asked Questions (FAQs)

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