Introduction to Arrays

Introduction to Arrays

An array is a collection of variables of the same data type stored in contiguous memory locations.

In this lesson, you will learn:

• How to declare and initialize arrays.
• How arrays are stored in memory.
• How to access and manipulate array elements.

Arrays are declared using square brackets [].

Example:

int numbers[5];

This creates an array that can store 5 integers.

Arrays can be initialized at the time of declaration:

int numbers[5] = {1, 2, 3, 4, 5};

Or, they can be initialized later:

numbers[0] = 10;

Array elements are accessed using an index (starting from 0).

Example:

int first = numbers[0];

This retrieves the first element of the array.

This program demonstrates how to store and access elements of an array.

#include <stdio.h>

int main() {
    int numbers[5] = {10, 20, 30, 40, 50};
    printf("First element: %d\n", numbers[0]);
    printf("Second element: %d\n", numbers[1]);
    return 0;
}

We can use a loop to iterate over an array:

for (int i = 0; i < 5; i++) { printf("%d ", numbers[i]); }

This prints all elements of the array.

This program prints all elements of an array using a loop.

#include <stdio.h>

int main() {
    int numbers[5] = {1, 2, 3, 4, 5};
    for (int i = 0; i < 5; i++) {
        printf("%d ", numbers[i]);
    }
    return 0;
}

Arrays are stored in contiguous memory locations.

Example:

int arr[3] = {10, 20, 30};

Memory Layout:

• arr[0] → Address A
• arr[1] → Address A + sizeof(int)
• arr[2] → Address A + 2*sizeof(int)

Summary

In this lesson, you learned:

• What arrays are and how they work.
• How to declare, initialize, and access array elements.
• How to loop through an array using a loop.

Next, we will explore multidimensional arrays in C!