What is an Array?

An array is a data structure that stores multiple values of the same data type under a single identifier. Each value is accessed by its index (position number). Arrays avoid the need to declare many separate variables.

1D Array visualised (scores[1:5])

Declaring Arrays in Cambridge Pseudocode

DECLARE scores : ARRAY[1:5] OF INTEGER
DECLARE names  : ARRAY[1:10] OF STRING

The format is: ARRAY[lower:upper] OF datatype. Cambridge typically uses 1-based indexing in exam questions.

Accessing and Assigning Array Elements

scores[1] ← 72
scores[2] ← 85
OUTPUT scores[3]   // outputs the value at index 3

Using Loops with Arrays

Input 5 values into an array

DECLARE scores : ARRAY[1:5] OF INTEGER
FOR i ← 1 TO 5
    INPUT scores[i]
NEXT i

Output all values

FOR i ← 1 TO 5
    OUTPUT scores[i]
NEXT i

Find the total and average

total ← 0
FOR i ← 1 TO 5
    total ← total + scores[i]
NEXT i
average ← total / 5
OUTPUT average

Find the maximum value

maximum ← scores[1]
FOR i ← 2 TO 5
    IF scores[i] > maximum THEN
        maximum ← scores[i]
    ENDIF
NEXT i
OUTPUT maximum

2D Arrays

A 2D array has rows and columns — like a table or grid. Useful for storing grids, timetables, or matrices.

DECLARE grid : ARRAY[1:3, 1:3] OF INTEGER

Accessing 2D array elements

grid[2, 3] ← 15   // row 2, column 3
OUTPUT grid[1, 1]

Nested loop to fill a 2D array

FOR row ← 1 TO 3
    FOR col ← 1 TO 3
        INPUT grid[row, col]
    NEXT col
NEXT row