Flashcards · 9618 · A Level Topic 20

Further Programming (A Level) flashcards

9 cards on A Level Topic 20, subtopics 20.1 to 20.2. Pick a subtopic or study them all.

Study mode needs JavaScript. Every card is listed below, so you can still cover the answers and test yourself.

All 9 cards

For a quick read-through or printing. Cover the right-hand side to test yourself.

What is the difference between low-level, imperative, object-oriented and declarative paradigms?: Low-level: works directly with the processor’s instructions and registers. Imperative (procedural): a sequence of statements that change state. Object-oriented: objects combining data and methods. Declarative: states facts and rules; the system works out how to answer a goal.
What are a class, an object and a constructor?: Class: a template defining attributes and methods. Object: an instance of a class. Constructor: the method that creates and initialises a new object.
What are encapsulation and inheritance?: Encapsulation: attributes are kept private and accessed only through the object’s methods (getters and setters). Inheritance: a subclass takes on the attributes and methods of its parent class and can add its own.
What is polymorphism?: A method with the same name behaves differently depending on the class of the object; a subclass can override an inherited method.
How does a declarative (logic) program answer a query?: It holds facts, e.g. parent(ali, sara), and rules, e.g. grandparent(X, Z) IF parent(X, Y) AND parent(Y, Z). A goal (query) is answered by matching it against the facts and rules.

What is an exception?: An unexpected event during program execution that disrupts the normal flow, such as a missing file, division by zero or invalid input.
What is exception handling and why is it used?: Code that catches an exception and deals with it (e.g. with try … except/catch) so the program does not crash and can report the problem or recover.
How do you read a record from a random file in 9618 pseudocode?: OPENFILE "Stock.dat" FOR RANDOM SEEK "Stock.dat", Position GETRECORD "Stock.dat", ThisItem CLOSEFILE "Stock.dat"
How do you add a record to a sequential file while keeping it in key order?: Read each record from the old file and write it to a new file until the correct position is reached; write the new record; copy the rest; then replace the old file with the new one.