Arrays, Lists and Records

Arrays

Store many values under one name, accessed by an index (usually from 0):

names ← ["Ali", "Bea", "Cal"]
OUTPUT names[0]      # Ali
names[2] ← "Cara"    # change an element

Iterating an array

FOR i ← 0 TO LEN(names) - 1
    OUTPUT names[i]
NEXT i

2D arrays

A table of rows and columns — grid[row][column]. Used for game boards, registers, spreadsheets.

grid[1][2]   # row 1, column 2

Records

Group related fields of different types about one item:

student = { name: "Sam" (string),
            age: 15 (integer),
            average: 72.5 (real) }

Exam tip

Arrays are zero-indexed on most specs: an array of 5 items has indices 0–4, so the last index is length − 1. Off-by-one errors are a classic bug.