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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 659 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.

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3 questions · 5 marks

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1Multiple choice1 markTranslators Swap Remove

A compiler translates source code into machine code.

Identify why a compiled program can be run on a computer that does not have the compiler installed.

[1 mark]
  • AThe code is translated again each time it is run
  • BThe code is translated one line at a time
  • CThe object code is saved as a separate file
  • DThe source code is saved with the program
Mark scheme
  • C The object code is saved as a separate file (1)
  • The only correct answer is C. The correct answer is the object code is saved as a separate file.
  • A is not correct because a compiled program is not translated again when it is run
  • B is not correct because translating one line at a time is how an interpreter works
  • D is not correct because the source code is not needed to run a compiled program
Example answers and how they were marked
Full marks1/1

C The object code is saved as a separate file

Why: Selected the saved object code, which can be run without the compiler being present (1).

No marks0/1

D The source code is saved with the program

Why: Near miss: it is the object code, not the source code, that is saved and run on another computer.

No marks0/1

B The code is translated one line at a time

Why: Confuses a compiler with an interpreter: a compiled program is translated as a whole and is not translated again when it is run.

2Describe2 marksTranslators Swap Remove

Source code can contain syntax errors.

Describe how a compiler and an interpreter differ in the way they deal with syntax errors.

[2 marks]
Mark scheme

Award up to two marks for a linked description such as:

  • The compiler reports all syntax errors after translation has finished (1) whereas the interpreter stops at the first error it finds (1)
  • The interpreter reports a syntax error as soon as it finds one (1) and does not translate/execute any more of the program (1)
  • The compiler continues translating after an error (1) and reports the errors at the end (1)
  • The interpreter stops translating when it reaches an error (1) but the compiler finishes translating before reporting errors (1)

Do not accept answers about fixing/correcting errors or about object code.

Do not award 'the compiler finds more errors' without saying errors are reported at the end.

Example answers and how they were marked
Full marks2/2

A compiler reports all the syntax errors at the end of translation, whereas an interpreter stops and reports the error as soon as it finds one.

Why: Compiler reports errors at the end (1) and interpreter stops/reports at the first error (1).

Some marks1/2

An interpreter stops translating when it finds a syntax error.

Why: Interpreter stops at the first error (1); no comparison with when the compiler reports errors.

No marks0/2

A compiler reports a syntax error immediately, before translating the rest of the program.

Why: Reverses the compiler's behaviour; it finishes translating before reporting errors.

3Explain2 marksTranslators Swap Remove

An interpreter translates a program one line at a time.

Explain why an interpreted program stops when it reaches a line that contains a syntax error.

[2 marks]
Mark scheme

Award up to two marks for a linked explanation such as:

  • The interpreter translates and executes each line in turn (1) so it cannot continue past a line it cannot translate (1)
  • The interpreter finds the error when it reaches that line (1) so it stops and displays an error message before later lines are executed (1)
  • Each line is translated just before it is executed (1) so a syntax error in that line prevents that translation/execution from happening (1)
  • The interpreter does not translate the whole program first (1) so it only discovers the error when that line is reached during execution (1)

For both marks, the expansion must follow/associate with the statement.

Do not accept 'the program crashes' without saying that the interpreter cannot translate/execute the line.

Do not accept answers about how a compiler reports errors.

Example answers and how they were marked
Full marks2/2

The interpreter translates each line just before it executes it, so when it reaches the line with the syntax error it cannot translate that line and stops.

Why: Line-by-line translation (1) linked to being unable to translate the faulty line, so stopping (1).

Some marks1/2

The interpreter translates one line at a time, so it stops at the error.

Why: Line-by-line translation (1); 'stops at the error' repeats the outcome and does not explain why it cannot continue.

No marks0/2

It stops because the compiler reports all errors at the end.

Why: Describes a compiler, not an interpreter; no credit.

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