C++ One-Dimensional Arrays

Introduction

One-dimensional arrays in C++ are used to store a sequence of elements of the same type in a linear structure. They provide a simple way to manage collections of data, such as lists of numbers or strings. Understanding how to use one-dimensional arrays is essential for efficient data manipulation and storage in your programs.

Declaring and Initializing One-Dimensional Arrays

Syntax for Declaring an Array

dataType arrayName[arraySize];

Example: Declaring and Initializing an Array

#include <iostream>
using namespace std;

int main() {
    int numbers[5]; // Declares an array of 5 integers

    // Initializing the array
    numbers[0] = 10;
    numbers[1] = 20;
    numbers[2] = 30;
    numbers[3] = 40;
    numbers[4] = 50;

    // Accessing and printing the array elements
    for (int i = 0; i < 5; i++) {
        cout << "numbers[" << i << "] = " << numbers[i] << endl;
    }

    return 0;
}

Output

numbers[0] = 10
numbers[1] = 20
numbers[2] = 30
numbers[3] = 40
numbers[4] = 50

Explanation

• int numbers[5]; declares an array named numbers of size 5.
• Each element of the array is accessed and initialized using the index.
• The for loop is used to iterate through the array and print each element.

Initializing Arrays at Declaration

You can also initialize an array at the time of declaration.

Example: Initializing an Array at Declaration

#include <iostream>
using namespace std;

int main() {
    int numbers[5] = {10, 20, 30, 40, 50}; // Declares and initializes an array

    // Accessing and printing the array elements
    for (int i = 0; i < 5; i++) {
        cout << "numbers[" << i << "] = " << numbers[i] << endl;
    }

    return 0;
}

Output

numbers[0] = 10
numbers[1] = 20
numbers[2] = 30
numbers[3] = 40
numbers[4] = 50

Explanation

• int numbers[5] = {10, 20, 30, 40, 50}; declares and initializes the array in a single line.

Array Size

The size of an array must be a constant expression and cannot be changed once declared. Using the sizeof operator, you can determine the size of the array.

Example: Determining the Size of an Array

#include <iostream>
using namespace std;

int main() {
    int numbers[] = {10, 20, 30, 40, 50}; // Array without explicitly specifying the size
    int size = sizeof(numbers) / sizeof(numbers[0]); // Calculate the size of the array

    cout << "The size of the array is: " << size << endl;

    return 0;
}

Output

The size of the array is: 5

Explanation

• int size = sizeof(numbers) / sizeof(numbers[0]); calculates the number of elements in the array by dividing the total size of the array by the size of one element.

Example Programs

Example 1: Finding the Largest Element in an Array

#include <iostream>
using namespace std;

int main() {
    int numbers[] = {10, 25, 5, 30, 15};
    int size = sizeof(numbers) / sizeof(numbers[0]);
    int max = numbers[0]; // Assume the first element is the largest

    for (int i = 1; i < size; i++) {
        if (numbers[i] > max) {
            max = numbers[i]; // Update max if the current element is larger
        }
    }

    cout << "The largest element in the array is: " << max << endl;

    return 0;
}

Output

The largest element in the array is: 30

Explanation

• The program initializes an array numbers and calculates its size.
• It iterates through the array to find the largest element and prints it.

Example 2: Summing Elements of an Array

#include <iostream>
using namespace std;

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

    for (int i = 0; i < size; i++) {
        sum += numbers[i]; // Add each element to sum
    }

    cout << "The sum of the elements in the array is: " << sum << endl;

    return 0;
}

Output

The sum of the elements in the array is: 150

Explanation

• The program initializes an array numbers and calculates its size.
• It iterates through the array to sum the elements and prints the total.

Example 3: Reversing an Array

#include <iostream>
using namespace std;

int main() {
    int numbers[] = {10, 20, 30, 40, 50};
    int size = sizeof(numbers) / sizeof(numbers[0]);

    cout << "Original array: ";
    for (int i = 0; i < size; i++) {
        cout << numbers[i] << " ";
    }
    cout << endl;

    // Reverse the array
    for (int i = 0; i < size / 2; i++) {
        int temp = numbers[i];
        numbers[i] = numbers[size - 1 - i];
        numbers[size - 1 - i] = temp;
    }

    cout << "Reversed array: ";
    for (int i = 0; i < size; i++) {
        cout << numbers[i] << " ";
    }
    cout << endl;

    return 0;
}

Output

Original array: 10 20 30 40 50
Reversed array: 50 40 30 20 10

Explanation

• The program initializes an array numbers and calculates its size.
• It iterates through the array to print the original elements.
• It reverses the array by swapping elements from the start with elements from the end.
• It iterates through the array again to print the reversed elements.

Conclusion

One-dimensional arrays in C++ provide a way to store and manage collections of data in a linear structure. This chapter covered how to declare, initialize, and access one-dimensional arrays. It also included example programs to demonstrate finding the largest element in an array, summing the elements of an array, and reversing an array. Understanding how to use one-dimensional arrays effectively will help you manage and process data efficiently in your programs. In the next chapter, we will explore multi-dimensional arrays in C++.