📅 Date: Jan 10, 2026
🔥 Topic: Arrays (Introduction & Syntax)

📦 The Problem with Variables

If I want to store marks of 50 students, creating 50 variables (m1, m2, m3...) is madness. That's where Arrays come in.

An Array is a collection of items of the SAME type stored in contiguous memory locations.

📝 Syntax

// datatype arrayName[size];
int marks[5]; // Stores 5 integers

🔢 Indexing (The Catch)

In C++ (and most languages), counting starts from 0, not 1.
First element: marks[0]
Last element: marks[4] (Size - 1)

💻 Day 10 Code: Basic Declaration

#include <iostream>
using namespace std;

int main() {
    // Declare and Initialize
    int luckyNumbers[4] = {7, 13, 21, 99};

    // Accessing elements
    cout << "First Number: " << luckyNumbers[0] << endl;
    cout << "Third Number: " << luckyNumbers[2] << endl;

    // Modifying an element
    luckyNumbers[1] = 100;
    cout << "New Second Number: " << luckyNumbers[1] << endl;

    return 0;
}

💭 Thoughts

Arrays are static; the size is fixed once declared. I need to be careful not to access an index that doesn't exist (like arr[10] in a size 5 array) or I'll get a Garbage Value.