This key facts covers Types of Validation within Input Validation for GCSE Computer Science. Revise Input Validation in 3.2 Programming for GCSE Computer Science with 15 exam-style questions and 8 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 2 of 6 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Types of Validation
| Type | What It Checks | Example |
|---|---|---|
| Range Check | Value within min/max limits | Age between 0 and 120 |
| Type Check | Data is correct data type | Age is an integer, not text |
| Length Check | Data has required length | Password at least 8 characters |
| Presence Check | Field isn't empty | Email address required |
| Format Check | Data matches expected pattern | Postcode: LL## #LL |
| Check Digit | Calculated digit matches | Last digit of barcode |
| Lookup Check | Value exists in a list | Country in list of countries |
Practice questions for Input Validation
A program asks the user to enter a score between 1 and 10. Which validation check should be used to ensure the number is within this range?
A registration form collects a username. The username must: not be blank, contain only letters and numbers, and be between 6 and 20 characters long. Identify three validation checks and explain what each one does for this input.