Write pseudocode to process array data

What is an Array? 📚

An array is like a row of lockers in a school hallway. Each locker has a number (the index) and can hold a single item. In programming, an array holds a fixed number of items of the same type, and we access each item using its index.

Indices start at 0, so the first locker is array[0], the second is array[1], and so on up to array[n-1] where n is the total number of lockers.

Key Properties of Arrays 🧩

• Fixed size: once created, the number of elements n cannot change.
• Homogeneous: all elements are of the same data type (e.g., all int).
• Indexed access: array[i] gives the i‑th element in constant time.

Accessing Elements 🔢

To read or change an element, we use its index:

value = array[3]   // read the 4th element
array[5] = 42      // write to the 6th element
  

Pseudocode Example 1: Sum of All Elements ➕

Goal: Calculate the total of all numbers stored in an array arr of length n.

1. Set total = 0.
2. For i = 0 to n-1 do:
   • Set total = total + arr[i].
3. Return total.

In LaTeX: $$\text{total} = \sum_{i=0}^{n-1} \text{arr}[i]$$

Pseudocode Example 2: Find the Largest Element 🏆

1. Assume the array is non‑empty. Set max = arr[0].
2. For i = 1 to n-1 do:
   • If arr[i] > max then set max = arr[i].
3. Return max.

Visualising an Array with a Table 📊

Here, arr[2] = 23 and arr[3] = 5.

Exam Tips for Arrays 🎯

• Read the question carefully: Identify whether you need to search, sort, or compute a value.
• Use clear variable names: e.g., index, sum, max to avoid confusion.
• Remember the index range: 0 to n-1. Off‑by‑one errors are common.
• Show your work: Even if the answer is a single number, write the pseudocode steps.
• Practice with different array sizes: Small arrays (3–5 elements) are easier to trace.