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Problem Solving and Design
Algorithm Design and Problem Solving · 4 question types
Exam Frequency Analysis
Past paper frequency (2018 to 2024)
This topic accounts for approximately 6% of your exam marks.
stable
Low
Stable6%
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:
Double-entry verification
The user enters the same value twice; the program checks that the two entries match.
Visual check
The system displays the entered data back to the user and asks them to confirm it is correct before continuing.
When to use which
- Double-entry verification is best for values the user cannot easily check by reading (passwords, where the characters are usually masked).
- Visual verification is best for values the user can easily eyeball (addresses, names, phone numbers).
The big-picture difference
| 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 |