CCEA A-Level Software Systems Development CL4
Software and the Development Environment
Defining Data: Types, Variables and Classes
Program Control Structures
Objects, Classes and Data Structures
Exception Handling and Managing Input and Output
Testing an Object Oriented Application
Graphical User Interface Objects and Events
Multiple Forms and Linking to Files
Designing, Testing and Evaluating an Event Driven Application
Reasons for Systems Development and Systems Methodologies
Managing Projects
Testing Strategies
Database Concepts and Entity Relationship Modelling
Normalisation and Structured Query Language
Project Management and the Systems Approach in Practice
Defining Requirements and Documenting the Design
Building a Desktop Solution with a Database
Testing and Evaluating the Solution
Software and the Development Environment
Compilers, interpreters and the build process
- 3 things to know
- AS Unit 1
Overview
Two differences between compilation and interpretation, syntax error and just-in-time compilation.
What you need to know
Answer each one before you reveal it.
How does a virtual machine allow one compiled program to run on several operating systems?
What does an interpreter do?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What does a compiler do?
Model answer
A compiler translates a complete source program into machine code or an intermediate code before it is run, producing an output file that can then be executed.
- 2
What does an interpreter do?
Model answer
An interpreter reads the source program a statement at a time and carries out each statement immediately, without producing a translated file.
- 3
What are two differences between compilation and interpretation?
Model answer
Compilation translates the whole program before anything runs and leaves a reusable output file, while interpretation translates during execution and must repeat the translation every time the program is run.
- 4
Why does a compiled program usually run faster than the same program interpreted?
Model answer
A compiled program is already in machine code and each instruction runs directly, whereas an interpreted program pays the cost of analysing each source statement again every time that statement is reached.
- 5
Why is an interpreter often preferred while a program is being written?
Model answer
An interpreter runs the program immediately with no build step and can report an error against the exact source line, so the edit-and-test cycle is much shorter.
- 6
What is a linker, and what problem does a linker solve?
Model answer
A linker joins the separately compiled object files and the library routines they use into one executable, resolving each reference to a routine defined in another file.
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