IGCSE Computer Science Paper 2 Definitions Worksheet: 8.1a Data Types and Variables (Modules 337–346)
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Key terms
Write what each term means, in your own words.
1
^
2
(a + b) / 2
3
DIV(a, b)
4
MOD(10, 3)
5
DIV(Total, Size) and MOD(Total, Size)
6
trace table
7
LENGTH(Text)
8
SUBSTRING(<string>, <start>, <length>)
9
SUBSTRING(Word, 1, 1)
10
UCASE(x)
Answer Key
IGCSE Computer Science Paper 2 · Modules 337–346 · Student wording will vary for definitions
1^ — The power operator. Radius ^ 2 raises Radius to the power 2, meaning Radius * Radius. It is worked out before multiplication, so Pi * Radius ^ 2 squares Radius first.
2(a + b) / 2 — Brackets are worked out first, then * and / before + and -. So (a + b) / 2 adds first, then divides, giving an average. Without brackets, only b is divided by 2.
3DIV(a, b) — Returns how many whole times b goes into a, discarding any remainder. DIV(10, 3) gives 3, but 10 / 3 gives 3.333. Both values are integers.
4MOD(10, 3) — MOD(a, b) gives the remainder when integer a is divided by integer b, so MOD(10, 3) is 1. A result of 0 means exact division. MOD(n, 2) is 0 for even n and 1 for odd n.
5DIV(Total, Size) and MOD(Total, Size) — DIV gives how many whole groups fit in the total, MOD gives what is left over. Together they split a total into whole units plus a remainder. E.g. 135 minutes is 2 hours 15.
6trace table — A table with one column per variable. Follow the program line by line and write each variable's new value after every assignment, so you can predict the final OUTPUT.
7LENGTH(Text) — Returns an INTEGER: the number of characters in the string, including spaces. LENGTH("Happy Days") returns 10 and LENGTH("") returns 0.
8SUBSTRING(<string>, <start>, <length>) — Returns part of a string: length characters taken from the start position. SUBSTRING("Happy Days", 1, 5) gives "Happy". The result is always a string.
9SUBSTRING(Word, 1, 1) — Position 1 is the first character in Cambridge pseudocode, so this returns the first letter. Some languages count from 0 instead, so state which numbering you use.
10UCASE(x) — UCASE(x) returns the string or CHAR x with every letter in upper case. UCASE("Happy") returns "HAPPY". The original variable only changes if you assign the result.