levo

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.

Your recallNot started
Process

State, in order, the stages that turn several source files into a running program.

Key term

How does a virtual machine allow one compiled program to run on several operating systems?

Key term

What does an interpreter do?

Questions from this subtopic

Each one with the model answer underneath.

  1. 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. 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. 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. 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. 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. 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.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Software and the Development Environment
Defining Data: Types, Variables and Classes
Program Control Structures
Objects, Classes and Data Structures

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

A null is the of one.
absencepresencetype

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AA null means no value has been recorded.
BZero and an empty string are values.
CA null is the absence of a value.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

An error is the mistake a person made.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Software and the Development Environment, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.