The Bouncer at the Door

Part of Input Validation · Section 1 of 6

IntroductionUnit: 3.2 ProgrammingGCSE

This introduction covers The Bouncer at the Door 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 1 of 6 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.

The Bouncer at the Door

Validation is like a bouncer at a club - checking everyone meets the entry requirements before letting them in. You can't have negative age, a 47-character postcode, or £999,999 in a £50 limit account. Validation catches these impossible values *before* they break your program. It doesn't guarantee data is correct (someone could enter age 25 when they're 52), but it ensures data is sensible and won't crash the system.

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. Type check
B. Range check
C. Length check
D. Presence check

1 markfoundation

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.

3 marksstandard

Quick recall flashcards

What is validation?

Checking input data is sensible and follows rules before processing

What is a type check?

Checking data is the correct data type (e.g., integer not text)

Types of Validation

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