IGCSE Computer Science Paper 2 Definitions Worksheet: 7a Program Development Life Cycle (Modules 60–70)
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Key terms
Write what each term means, in your own words.
1
REPEAT INPUT UNTIL valid
2
AND
3
valid but wrong
4
validation check
5
visual check
6
double entry check
7
UNTIL Password1 = Password2
8
validation vs verification
9
validation loop
10
test data
Answer Key
IGCSE Computer Science Paper 2 · Modules 60–70 · Student wording will vary for definitions
1REPEAT INPUT UNTIL valid — A REPEAT loop around INPUT that keeps asking for a value and shows an error message each time the check fails. The UNTIL condition is the valid range, so the loop ends only on valid data.
2AND — Joins several validation checks into one condition, so the input must pass every check. Examples: presence and length together, or range and type together.
3valid but wrong — Validation only checks data is reasonable and in the right form, so a valid value can still be wrong, e.g. age 15 typed instead of 51. Verification is also needed.
4validation check — A test matched to the field: range for age, length and type for PIN, presence for name, format for dates or postcodes, check digit for ISBN. Always justify the choice.
5visual check — A check where a person reads the data on screen and compares it by eye with the original source to spot mistakes. It is done by a person, not the program, and can miss errors.
6double entry check — Data is entered twice and the two entries are compared. Any difference shows a mistake, so the user must enter it again. It misses the same mistake made twice.
7UNTIL Password1 = Password2 — Double entry check: INPUT the value twice inside a REPEAT loop and stop only when both are equal. Output a message if they do not match, so typing mistakes are caught.
8validation vs verification — Validation checks data is acceptable, like an age range check. Verification checks it was typed correctly, like double entry. A scenario may need one or both.
9validation loop — DECLARE the variable, OUTPUT a prompt, INPUT the value, OUTPUT an error message if it fails the check, and REPEAT ... UNTIL the value is acceptable.
10test data — The input values chosen before testing, such as normal, abnormal, extreme and boundary values, used to run a program so its results can be compared with the expected results.