IGCSE Computer Science Paper 2 Definitions Worksheet: 8.2 Arrays (Modules 449–458)
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Key terms
Write what each term means, in your own words.
1
ARRAY[1:30]
2
upper - lower + 1
3
meaningful identifier
4
StudentNames[1] ← "Ali"
5
OUTPUT StudentNames[1]
6
Marks[Index]
7
Array[n+1]
8
index out of range
9
FOR Index ← 1 TO 30
Answer Key
IGCSE Computer Science Paper 2 · Modules 449–458 · Student wording will vary for definitions
1ARRAY[1:30] — The number before the colon is the lower bound, the first index. ARRAY[1:30] starts at 1, ARRAY[0:29] starts at 0. Both hold 30 elements, so always state the lower bound.
2upper - lower + 1 — The number of elements in a 1D array: upper bound minus lower bound plus one. ARRAY[0:9] holds 9 - 0 + 1 = 10 elements, and ARRAY[5:9] holds 5.
3meaningful identifier — An array name that says what its elements hold, like StudentNames not A. It must never be a keyword such as INPUT or FOR, and upper or lower case makes no difference.
4StudentNames[1] ← "Ali" — Stores a value in one array element using the assignment operator ←. The value must match the array's data type, and it replaces any old value already in that element.
5OUTPUT StudentNames[1] — Reading an element: Name[index] in OUTPUT or an expression gives the value stored in that element. Reading only uses the value, so the element stays unchanged.
6Marks[Index] — A variable inside the brackets picks the element whose index matches its value. Change Index (an INTEGER) and the same statement reaches a different element of Marks.
7Array[n+1] — An index can be an expression like n+1. The expression is worked out first, then that element is used. It must stay within the array's bounds. Example: n=3 gives Array[4].
8index out of range — An error caused by using an index below the lower bound or above the upper bound, so the element does not exist. Example: Marks[31] in ARRAY[1:30] or Marks[0] when the lower bound is 1.
9FOR Index ← 1 TO 30 — A count-controlled loop. It repeats the indented statements once for each value of Index, from 1 up to 30, going up by 1 each time. NEXT Index closes the loop.