Chess Club Weekly Attendance

Arrays let you group several related values under one name instead of inventing a new variable for each one. int[] attendance = { 9, 12, 7 } creates an array of a fixed size, and you reach each value by its index, starting at 0 — so attendance[0] is the first value. An array's .Length tells you how many elements it holds, and looping for (int i = 0; i < someArray.Length; i++) is the standard, safe way to visit every valid index without going past the end.

Worked example

Here's an array of three quiz attempt scores, with the best one picked out:

int[] attempts = { 62, 78, 71 };
int best = attempts[0];

for (int i = 0; i < attempts.Length; i++)
{
    Console.WriteLine($"Attempt {i + 1}: {attempts[i]}");
    if (attempts[i] > best)
    {
        best = attempts[i];
    }
}

Console.WriteLine($"Best attempt: {best}");

Attempt 1: 62
Attempt 2: 78
Attempt 3: 71
Best attempt: 78

The loop's condition, i < attempts.Length, stops right after visiting the last valid index, which here is 2 since Length is 3.

Your turn

The starter code stores a week of chess club attendance in an array and prints each night's count alongside its total. Its loop condition is i <= attendance.Length, which lets i reach a value equal to Length itself — one past the last valid index — and that crashes the program when it tries to read attendance[5] from a 5-element array. Fix the condition so the loop only visits valid indices.

If something goes wrong

An IndexOutOfRangeException almost always means a loop condition used <= with .Length where it needed < (or started counting from the wrong place). If the program runs but the total looks wrong, check that you're not skipping the first or last element — trace through which indices i actually takes for a small array before trusting the sum.