Algorithm Design and Problem Solving · 4 question types
Past paper frequency (2018 to 2024)
This topic accounts for approximately 6% of your exam marks.
Decomposition, abstraction and structure charts appear as design-focused questions.
Verification is a check that the data entered into the system matches the data that was intended.
Validation asks "Is this input sensible?" Verification asks "Did the user actually mean to type this?"
Two common verification methods:
The user enters the same value twice; the program checks that the two entries match.
The system displays the entered data back to the user and asks them to confirm it is correct before continuing.
| Validation | Verification | |
|---|---|---|
| What it asks | Is the input plausible / sensible? | Did the user actually mean to type this? |
| Performed by | The program (automatically), based on rules | The user (with a prompt from the program) |
| Methods | Range, length, type, presence, format, check digit | Double-entry, visual check |
| Catches | Invalid types, blank fields, out-of-range values, typos in formatted codes | Typing the wrong but plausible value (e.g. wrong email address) |
| Limit | Can confirm input is sensible, not that it is correct | Can confirm the user typed what they meant, but not that the meaning is right |