Programming
What's covered
Key facts
Arithmetic Operations: Including Integer Division and Modulo
In AQA pseudo-code the keyword for integer division is DIV.
Authentication Routines
Authentication identifies who you are; authorisation decides what you are allowed to do.
Boolean Operators: NOT, AND, OR
age >= 18 AND has_ticket is true only when both conditions hold.
Casting
Not every value can be converted: a string such as "dog" cannot be turned into an integer.
Character-to-Code Conversion
The ASCII code of the character '1' is 49, not the integer 1.
Code Maintainability and Comments
A comment is a note added to code to explain its purpose; it is ignored by the computer when the program runs.
Data Types: Integer, Real, Boolean, Character, String
The five data types named on the AQA 8525 spec are integer, real, Boolean, character and string.
Data Validation Routines
A format check tests that data matches an expected pattern, e.g. UK postcode LL1 1LL.
Defensive Design
Anticipating misuse means a programmer thinks about how a user could accidentally or deliberately cause a program to fail, and writes code to prevent harm.
File Handling
Appending writes new data to the end of a file, keeping the data already in it.
Practice questions with answers
A taste of the 244 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
What is the value of 10 DIV 3?
- •One (the result minus two)
- •Ten (the dividend value itself)
- ✓Three (the integer part only)
- •Zero (no integer part at all)
What is the most common form of authentication?
- •A handshake captured by the computer's camera
- •A signature signed on a physical form
- ✓A username and password combination
- •A weekly emailed code sent to the user
When does an AND expression return true?
- •When at least one operand is true
- ✓When both operands are true
- •When neither operand is true at all
- •When the operands are different in value
What data type is keyboard input usually received as, even when digits are typed?
- •Boolean
- •Integer
- •Real
- ✓String
What does ASCII let us do with characters?
- •Compress characters to reduce file size
- •Display characters in different fonts and sizes
- •Encrypt characters for secure transmission
- ✓Represent characters as numbers
Why are subroutines used when structuring a program?
- •To convert the code into binary faster
- •To make the program run more quickly
- ✓To split it into smaller reusable parts
- •To stop users entering invalid data
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