IGCSE Computer Science Paper 2 Definitions Worksheet: 7a Program Development Life Cycle (Modules 37–46)
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Key terms
Write what each term means, in your own words.
1
LENGTH(<string>)
2
SUBSTRING("Happy Days", 1, 5)
3
UCASE(x) and LCASE(x)
4
IF condition THEN ... ENDIF
5
ELSE
6
nested IF
7
CASE OF
8
FOR Index ← 1 TO 30
9
STEP
10
WHILE condition DO ... ENDWHILE
Answer Key
IGCSE Computer Science Paper 2 · Modules 37–46 · Student wording will vary for definitions
1LENGTH(<string>) — Returns the number of characters in a string as an integer, counting spaces. LENGTH("Happy Days") returns 10. Used in length checks.
2SUBSTRING("Happy Days", 1, 5) — SUBSTRING(string, start, length) returns length characters beginning at position start. Position 1 is the first character, so this returns "Happy".
3UCASE(x) and LCASE(x) — UCASE returns a string or character in upper case, e.g. UCASE("Happy") gives "HAPPY". LCASE returns it in lower case, e.g. LCASE('W') gives 'w'.
4IF condition THEN ... ENDIF — Runs the statements between THEN and ENDIF only when the condition is TRUE. If the condition is FALSE, they are skipped. This form has no ELSE part.
5ELSE — Gives IF a second path. The THEN statements run when the condition is TRUE and the ELSE statements run when it is FALSE. Exactly one path runs, never both.
6nested IF — An IF statement written inside the THEN or ELSE part of another IF. It only runs when the outer condition leads to it, and each IF needs its own ENDIF.
7CASE OF — Runs the statement beside the first value that matches the variable. An optional OTHERWISE clause, placed last, runs if nothing matches. ENDCASE closes the structure.
8FOR Index ← 1 TO 30 — Repeats the code once for each integer from 1 to 30 inclusive, up to NEXT Index. Runs once if both values are equal and not at all if the start value is bigger.
9STEP — Used in a FOR loop to set how much the loop variable changes each time. STEP 2 counts in twos and STEP -1 counts down. The loop stops when the value goes past the end.
10WHILE condition DO ... ENDWHILE — A loop that tests its condition first, then repeats its statements while the condition is TRUE. If it is FALSE at the start, the loop never runs. ENDWHILE marks the end of the loop.