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2.3 Producing robust programs and 2.4 Boolean logic

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do the logic operators AND, OR and NOT work, and how do you build a truth table?

Boolean logic: the operators AND, OR and NOT, applying them to expressions, and constructing truth tables for simple logic statements including combinations of operators.
An OCR J277 2.4.1 answer on Boolean logic: the operators AND, OR and NOT, applying them to expressions, and constructing truth tables for simple logic statements and combinations of operators.
10 min answer →

How do you design a program that copes with unexpected input and is easy to maintain?

Defensive design: anticipating misuse, input validation and sanitisation, authentication, and writing maintainable programs through comments, indentation and sensible naming.
An OCR J277 2.3.1 answer on defensive design: anticipating misuse, validating and sanitising input, authentication, and writing maintainable programs with comments, indentation and sensible variable names.
10 min answer →

What are syntax errors and logic errors, and how do you tell them apart?

The two main types of programming error: syntax errors and logic errors, what causes each, how they are found, and how they differ.
An OCR J277 2.3.2 answer on the two main types of programming error: syntax errors (breaking the rules of the language) and logic errors (the program runs but gives the wrong result), what causes each, and how they are found and corrected.
9 min answer →

How are the AND, OR and NOT operators drawn as logic gates and combined into circuits?

Logic gates: the AND, OR and NOT gates and their symbols, reading and drawing simple logic circuit diagrams, and producing the truth table for a combination of gates.
An OCR J277 2.4.1 answer on logic gates: the AND, OR and NOT gates and their symbols, reading and drawing simple logic circuit diagrams, and working out the truth table for a combination of gates.
10 min answer →

Why do we test programs, what kinds of testing are there, and what test data should you use?

The purpose of testing, the difference between iterative and terminal (final) testing, and the types of test data (normal, boundary and erroneous or invalid), with how to choose suitable test data.
An OCR J277 2.3.2 answer on testing: the purpose of testing, iterative versus terminal (final) testing, and the three types of test data (normal, boundary and erroneous or invalid), with how to choose suitable test data and build a test plan.
10 min answer →