Languages And Environments Flashcards
What is the purpose and main characteristics of a declarative programming language. Give an example.
Code defines a set of logical statements - facts and rules - rather than carrying out instructions in a sequence.
Searches logical statements for conclusions as it is run.
Example - Prolog, used for artificial intelligence applications. It defines sets of unordered rules and facts known as a knowledge base.
What is the purpose and main characteristics of object-oriented programming? Give an example.
Classes are defined which include variables and methods (special procedures which define how the object behaves)
Each object created during the execution of an o-o program is called an instance of a class.
New objects will have a copy of the data required to define the object and may inherit data defined in other classes.
Example - Game programming and to model real-life situations (due to easy creation and deletion of objects)
Why do programs need to be translated into binary?
All processors have their own instruction set. Before execution on a specific processor, programs must be translated into binary which correspond to the processors instruction set.
Demonstrate the relationship between a computers instruction set and its program code.
-Low level languages like Assembly language have a 1:1 relationship between commands and binary machine code.
What is meant by ‘High level language programs are described as platform independent, whereas binary programs are platform specific’?
HLL programs are compiled to run on different processors with different instruction sets.
Binary programs must be written according to the platform in which they are to be run on - on only one computer with a single instruction set.
Which programming language would be best for writing a touch screen phone application? Why?
Object oriented because different objects to be selected or dragged by touch are used.
Why does every programming language have a strict set of rules defining how lines of code should be formatted?
So it is possible for a compiler to be created to translate the code as users would be prevented from entering instructions in any way they like.
Why do most assembly languages instructions still need to be translated into binary?
The computers hardware is built to store and process only binary and so all data and instructions must be stored and processed as binary.
What is the purpose and main characteristics of a procedural language program? Give an example.
Written out in blocks of code called subroutines, procedures or functions.
Program carries out instructions one at a time
Examples include - Visualbasic, TrueBASIC,
Why are low-level languages used?
Allow for the optimisation of code because of a one to one relationship to machine code
Architecture/Platform dependent language
Low level language
Architecture/Platform independent language
High level language
Parameter
Data value which can be passed to a subroutine at run time.
Declarative Languages contain
Facts and rules
Feature of a declarative language and what is it used for?
Pattern matching
rules - join existing facts together using :- ( if ) and logic operators ( AND, OR )
State
The value of an attribute/instance variable at any given time within the context of object oriented programming
Inheritance and maintenance
Errors fixed in a super class/sub class get reflected automatically in sub classes/instances when using object oriented languages This saves time
Translator
Required for the creation of executable code
Software held in RAM translates source code into executable code
Uses interpreter/compiler
Operation/Method (Object-oriented)
Code which changes the state of an object’s attribute in object oriented environment
Instruction Set
The built in instructions processors are manufactured with
Before a program can be executed on a specific processor is must be translated into binary which corresponds to the processors instruction set
Why is it unlikely for a programmer to write LLL instructions in binary?
Code is difficult to read
Hard to find any mistakes when inputting long lists of 1s and 0s
Assembly Language
Used to write LLL instructions
Consists of codes that represent each instruction from the instruction set
Must still be translated into binary equivalent before program can be run
High Level Language
Written in English, using a strict syntax
Completed HLL instructions translated into a separate binary program using a compiler
Simpler way to program
Not as efficient as LLL code
Types of high level language
Procedural, declarative, object-oriented
