Array

An array is a data structure used to store multiple values in a single variable.
Each value stored in an array is called an element, and every element has an index that represents its position in the array.

In most programming languages:

• array indexes start from 0
• elements are stored sequentially in memory

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Why Use Arrays?

Arrays are useful when:

• you need to store many values at once
• the values are related to each other
• you want to process data using loops

Instead of creating many separate variables, an array allows you to group data together.

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Array Index

The index is used to access elements inside an array.

Example:

Index:   0   1   2
Values: 10  20  30

• array[0] → first element
• array[1] → second element

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Creating an Array (Conceptually)

In general, creating an array involves three steps:

1. Declare an array variable
2. Define the array size (in some languages)
3. Assign values to each element

Depending on the programming language, these steps can be done:

• in one statement, or
• separately

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Example: Array Declaration

Python

numbers = [10, 20, 30]

C

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

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Accessing Array Elements

You can access elements using their index.

Example (Python)

numbers = [10, 20, 30]
print(numbers[0])   # Output: 10

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Data Types in Arrays

In many languages:

• all elements in an array must have the same data type

Example (C):

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

In some languages:

• arrays can store different data types

Example (Python):

data = [1, "apple", 3.14, True]

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Multidimensional Arrays

A multidimensional array is an array that contains other arrays.

The most common example is a 2D array (array inside an array).

Example (Python)

matrix = [
    [1, 2, 3],
    [4, 5, 6]
]

Here:

• matrix[0][1] → value 2
• two indexes are used (row and column)

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In Short

• An array stores multiple values in one variable
• Each element has an index, usually starting from 0
• Arrays help organize data and work efficiently with loops
• Arrays can be one-dimensional or multi-dimensional

Arrays are a fundamental concept and prepare you for:

• loops
• data structures
• algorithm design