Pseudocode FUNCTION ... RETURNS ... RETURN ... ENDFUNCTION

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Quick Questions

Shade in the A or B circle for each question.

1. Which header correctly starts a Cambridge pseudocode function that takes a whole number and gives back a whole number?

A FUNCTION Double(Num : INTEGER) RETURNS INTEGER

B FUNCTION Double(Num : INTEGER) INTEGER

2. Which line sends a calculated value back from a function called Square?

A RETURN Num * Num

B OUTPUT Num * Num

3. How should a function definition be closed?

A ENDPROCEDURE

B ENDFUNCTION

4. Which statement about functions is true?

A A function never sends a value back

B A function sends a value back using RETURN

5. Which is the correct way to use the function Double inside an expression?

A Total ← Double(5) + 1

B CALL Double(5) + 1

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1FUNCTION Double(Num : INTEGER) RETURNS INTEGER		ASends the calculated value Num multiplied by 2 back to the part of the program that called the function
2RETURN Num * 2		BStarts a function called Double that takes an integer parameter Num and will send back an integer value
3A function is closed with ENDFUNCTION after its RETURN line, and the function body is indented		CThe header is missing RETURNS INTEGER, so the type of value sent back is not stated
4A function call can be used inside an expression because it gives back a value		DFUNCTION Square(N : INTEGER) RETURNS INTEGER RETURN N * N ENDFUNCTION
5FUNCTION Double(Num : INTEGER) RETURN Num * 2 ENDFUNCTION		EOUTPUT is used instead of RETURN, so the value is only displayed and not sent back to the caller
6FUNCTION Double(Num : INTEGER) RETURNS INTEGER OUTPUT Num * 2 ENDFUNCTION		FTotal ← Square(5) + 10

Definitions

FUNCTION Name(Param : TYPE) RETURNS TYPE

Fill in the Blanks

Complete each line of code by filling in the missing parts.

________ Square(N : INTEGER) RETURNS INTEGER RETURN N * N ENDFUNCTION

FUNCTION Half(N : _______) RETURNS REAL RETURN N / 2 ENDFUNCTION

FUNCTION Cube(N : INTEGER) _______ INTEGER RETURN N * N * N ENDFUNCTION

FUNCTION AddVAT(P : REAL) RETURNS REAL ______ P * 1.2 ENDFUNCTION

INPUT Price Total ← AddVAT(_____) + 5 OUTPUT Total

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A FUNCTION Sq(N INTEGER)

B RETURNS INTEGER

C RETURN N * N

D ENDFUNCTION

E OUTPUT Sq(3)

Question 2

A FUNCTION Half(N : REAL)

B RETURN REAL

C RETURN N / 2

D ENDFUNCTION

Question 3

A FUNCTION Cube(N : INTEGER)

B RETURNS STRING

C RETURN N * N * N

D ENDFUNCTION

E OUTPUT Cube(3)

Question 4

A PROCEDURE Tax(P : REAL)

B RETURNS REAL

C RETURN P * 0.2

D ENDFUNCTION

Question 5

A FUNCTION Cost(P : REAL)

B RETURNS REAL

C OUTPUT P * 1.2

D ENDFUNCTION

E OUTPUT Cost(10)

Answer Key

Pseudocode FUNCTION ... RETURNS ... RETURN ... ENDFUNCTION

Section A: Quick Questions

A — FUNCTION Double(Num : INTEGER) RETURNS INTEGER

A — RETURN Num * Num

B — ENDFUNCTION

B — A function sends a value back using RETURN

A — Total ← Double(5) + 1

Section B: Match the Pairs

FUNCTION Double(Num : INTEGER) RETURNS INTEGER → Starts a function called Double that takes an integer parameter Num and will send back an integer value

RETURN Num * 2 → Sends the calculated value Num multiplied by 2 back to the part of the program that called the function

A function is closed with ENDFUNCTION after its RETURN line, and the function body is indented → FUNCTION Square(N : INTEGER) RETURNS INTEGER RETURN N * N ENDFUNCTION

A function call can be used inside an expression because it gives back a value → Total ← Square(5) + 10

FUNCTION Double(Num : INTEGER) RETURN Num * 2 ENDFUNCTION → The header is missing RETURNS INTEGER, so the type of value sent back is not stated

FUNCTION Double(Num : INTEGER) RETURNS INTEGER OUTPUT Num * 2 ENDFUNCTION → OUTPUT is used instead of RETURN, so the value is only displayed and not sent back to the caller

Section C: Definitions

FUNCTION Name(Param : TYPE) RETURNS TYPE — Starts a function that takes a typed parameter and RETURNS a value of the stated type. RETURN sends the value back, ENDFUNCTION closes it, and you can call it inside an expression.

Section D: Fill in the Blanks

FUNCTION Square(N : INTEGER) RETURNS INTEGER
  RETURN N * N
ENDFUNCTION

FUNCTION Half(N : INTEGER) RETURNS REAL
  RETURN N / 2
ENDFUNCTION

FUNCTION Cube(N : INTEGER) RETURNS INTEGER
  RETURN N * N * N
ENDFUNCTION

FUNCTION AddVAT(P : REAL) RETURNS REAL
  RETURN P * 1.2
ENDFUNCTION

INPUT Price
Total ← AddVAT(Price) + 5
OUTPUT Total

Section E: Spot the Error

A — A parameter must be written as Name : TYPE. The colon is missing, so it should be FUNCTION Sq(N : INTEGER).

B — The function header states the type with the keyword RETURNS. RETURN is only used inside the body to send a value back. It should be RETURNS REAL.

B — The function returns the result of a multiplication, which is a number. The RETURNS type must match the value returned, so it should be RETURNS INTEGER.

A — This subroutine returns a value and ends with ENDFUNCTION, so it must start with FUNCTION, not PROCEDURE. A procedure does not return a value.

C — OUTPUT only displays the value. It does not send it back to the caller. A function must use RETURN P * 1.2 to give its result back.