← IGCSE Computer Science Paper 1

Interpreter for development, compiler for the final program

Use an interpreter while developing to test and fix code quickly, then compile the final program once into a fast executable to give users without the source code.

Part of: IGCSE Computer Science 0478 — 4.2 Programming Languages, Translators and IDEs — Module 25

Understanding Interpreter for development, compiler for the final program in IGCSE Computer Science Paper 1

What it does: The student edits one line and runs it immediately, which is the quick test and fix cycle an interpreter allows during development. Compiling once creates a game.exe file to give to users, so the source code stays with the developer. An interpreter lets the programmer run the code immediately without waiting for full compilation. A compiler translates the whole program once. The executable can then be run again and again without translating it again. The benefit of an interpreter is quick testing and fixing. It is usually slower than running compiled code.

Common mistakes: The string 'developing' does not match 'development' in the IF test, so the interpreter branch would never run. Line 1 should be phase <- 'development'. An IF statement must end with THEN. Line 2 should be IF phase = 'release' THEN.

Class: _____________________ · Name: _____________________ · Date: _________

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This module's key terms are also in a printable crossword (Modules 440–449) and word search (Modules 440–463).

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Learning

Duo

Which translator is usually used while a programmer is still writing and testing the program?

CompilerInterpreter

Matches

Developer compiles the whole program again after every small change while testing, and waits each time

↓

Recompiling the full program after every small edit wastes time during development. An interpreter should be used for quick testing and fixing.

Applying

Meanings

Term

interpreter for development, compiler for release

Meaning

Use an interpreter while developing to test and fix code quickly, then compile the final program once into a fast executable to give users without the source code.

Practice

WHILE program has errors

Testing

Gaps

developmentTranslator ←

Check Answer

Spots

1phase <- 'developing'

2IF phase = 'development' THEN

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Quick Questions

1. Which translator is usually used while a programmer is still writing and testing the program?

A. Interpreter ✓

B. Compiler

An interpreter runs the code line by line straight away, so the programmer can test and fix it quickly during development.

2. A programmer changes one line and wants to see the result at once. What helps most?

A. A compiler, because it must rebuild the whole program before every test

B. An interpreter, because there is no wait for the whole program to compile ✓

An interpreter lets the programmer run the code immediately without waiting for full compilation.

3. Which translator is normally used to produce the final version of the program for release?

A. Compiler ✓

B. Interpreter

The final program is compiled once into an executable file that runs quickly for the users.

4. A company wants to give customers a program without sharing its source code. What should it do?

A. Give users the source code and an interpreter

B. Compile the program and give users the executable file ✓

A compiled executable does not include the source code, so the company's code stays hidden from users.

5. Which statement is true about the final release of a program?

A. It is compiled once, then the executable can be run many times ✓

B. It must be translated again every time a user runs it

A compiler translates the whole program once. The executable can then be run again and again without translating it again.

Match the Pairs

Run the program line by line while writing it → Using an interpreter during development so you can test and fix code quickly without waiting for full compilation

Compile the finished program once for release → Using a compiler to translate the final program into a fast executable file that users can run

While developing, an interpreter lets you test a small change straight away with no wait for full compilation → print(total) # edit, run, see the result at once

For release, the program is compiled once and users receive an executable without the source code → compile game.src -> game.exe

Developer compiles the whole program again after every small change while testing, and waits each time → Recompiling the full program after every small edit wastes time during development. An interpreter should be used for quick testing and fixing.

Company sends customers the source code and an interpreter so they can run the final program → The final program should be compiled once into an executable. Giving out source code is less secure and the program runs slower when interpreted.

Key Term

interpreter for development, compiler for release

Use an interpreter while developing to test and fix code quickly, then compile the final program once into a fast executable to give users without the source code.

Fill in the Blanks

1. developmentTranslator ← interpreter

Hint: Type the translator that runs code line by line so you can test and fix quickly while developing.

2. releaseTranslator ← compiler

Hint: Type the translator used once on the finished program to make a fast file for release.

3. sendToUsers(executable)

Hint: Type the kind of file the compiler produces, which users can run without seeing the source code.

4. compileCountForRelease ← 1

Hint: Type the number of times the final program needs to be compiled for release.

5. WHILE bugsExist testWith(interpreter) ENDWHILE

Hint: Type the loop keyword that repeats testing and fixing while errors still remain.

Spot the Error

Question 1

A phase <- 'developing'

B IF phase = 'development' THEN

C tool <- 'interpreter'

D ENDIF

Line A — The string 'developing' does not match 'development' in the IF test, so the interpreter branch would never run. Line 1 should be phase <- 'development'.

Question 2

A phase <- 'release'

B IF phase = 'release'

C tool <- 'compiler'

D ENDIF

Line B — An IF statement must end with THEN. Line 2 should be IF phase = 'release' THEN.

Question 3

A phase <- 'development'

B tool <- 'compiler'

C OUTPUT 'Test and fix quickly'

Line B — During development an interpreter is used because it lets you test and fix code quickly. A compiler is for the final release. Line 2 should be tool <- 'interpreter'.

Question 4

A phase <- 'release'

B tool <- 'compiler'

C delivered <- 'executable file'

D OUTPUT 'Users: ' + source

Line D — The variable source was never created, so the program fails. The line should use the variable delivered, which holds the executable file given to users.

Question 5

A REPEAT

B RUN with interpreter

C FIX the error found

D UNTIL errors remain

Line D — The test-and-fix cycle should repeat until there are no errors left, not until errors remain. Line 4 should be UNTIL no errors remain.

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