Subroutines, arrays and files — GCSE Computer Science practice questions

Question 1

A running app uses this function to convert a distance:

```pseudocode
FUNCTION ToMiles(Kilometres : REAL) RETURNS REAL
   RETURN Kilometres * 0.62
ENDFUNCTION
```

Which term describes Kilometres in the first line of the function?

Accepted Answer

C: A parameter. Kilometres is declared in the brackets of the function header with its data type, so it is a parameter: it receives the value passed in when the function is called, such as 10 in ToMiles(10). The value sent back is Kilometres * 0.62, given by RETURN; RETURNS REAL only states its data type.

Question 2

Priya's quiz game has a procedure with the header PROCEDURE ShowLevel(Level : INTEGER). The procedure is written once, near the top of the program. Further down, a CALL ShowLevel statement appears in four different places, each with a different level number in the brackets.

Which statement is correct?

Accepted Answer

B: The procedure is defined once and called four times; each call runs the procedure's statements using the value passed in.. Writing the header, body and ENDPROCEDURE once is defining the procedure. Each of the four CALL statements is a call: the program jumps to the procedure, runs its statements with the argument given in that call, then carries on after the CALL. So the procedure is defined once and called four times, with a new Level value each time.

Question 3

A game uses this pseudocode:

```pseudocode
DECLARE Score : INTEGER

PROCEDURE Bonus(Points : INTEGER)
   DECLARE Score : INTEGER
   Score ← Points * 2
   OUTPUT Score
ENDPROCEDURE

Score ← 5
CALL Bonus(4)
OUTPUT Score
```

What is output?

Accepted Answer

A: 8 then 5. Inside Bonus, the parameter Points is 4 and the local variable Score is set to 4 × 2 = 8, which is output. The local Score disappears when the procedure ends. The last OUTPUT is in the main program, so it uses the global Score, which is still 5. The output is 8 then 5.