The RETURN statement

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Quick Questions

Shade in the A or B circle for each question.

1. Which statement sends a value back to the place where a function was called?

A OUTPUT Total

B RETURN Total

2. Which function ends with a correct RETURN of an expression?

A RETURN Number1 * Number1

B RETURN INTEGER Number1 * Number1

3. Where does the RETURN statement normally go in a function?

A At the very start, before the function header

B As the last statement, just before ENDFUNCTION

4. A function has this line: RETURN Result. What does it return?

A The value currently stored in the variable Result

B The word "Result" as text

5. FUNCTION Double(N : INTEGER) RETURNS INTEGER has RETURN N * 2 on line 2 and OUTPUT "Done" on line 3. What happens when Double(5) is called?

A It returns 10 and "Done" is never output

B It returns 10 and then outputs "Done"

Match the Pairs

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

Left column		Right column
1RETURN Number1 * Number1		ARETURN has no value or expression after it, so nothing is sent back. It should be RETURN A + B.
2RETURN Total		BFUNCTION Double(Num : INTEGER) RETURNS INTEGER RETURN Num * 2 ENDFUNCTION
3A function ends with RETURN as its last statement, sending back its answer		CThe function uses OUTPUT instead of RETURN, so no value is sent back to the caller. It should be RETURN Number1 * Number1.
4RETURN ends the function, so any statement written after it in the same path never runs		DRETURN Result OUTPUT "Done"
5FUNCTION Square(Number1 : INTEGER) RETURNS INTEGER OUTPUT Number1 * Number1 ENDFUNCTION		ESends the value stored in the variable Total back to the place where the function was called
6FUNCTION Add(A : INTEGER, B : INTEGER) RETURNS INTEGER RETURN ENDFUNCTION		FWorks out the square of Number1 and sends that value back to where the function was called

Definitions

RETURN

Fill in the Blanks

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

FUNCTION Sq(Number1 : REAL) RETURNS REAL ______ Number1 * Number1 ENDFUNCTION

FUNCTION Sq(Number1 : REAL) RETURNS REAL RETURN Number1 _ Number1 ENDFUNCTION

Sum ← A + B RETURN ___ ENDFUNCTION

Result ← Sq(5) OUTPUT ______

FUNCTION Pass(Mark : INTEGER) RETURNS BOOLEAN RETURN Mark __ 50 ENDFUNCTION

Spot the Error

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

Question 1

A FUNCTION Sq(N) RETURNS INTEGER

B Result ← N * N

C RETURN

D ENDFUNCTION

Question 2

A FUNCTION Sq(N) RETURNS INTEGER

B OUTPUT N * N

C ENDFUNCTION

D OUTPUT Sq(5)

Question 3

A PROCEDURE Half(N)

B RETURN N / 2

C ENDFUNCTION

Question 4

A FUNCTION Pay(H) RETURNS REAL

B Total ← H * 12.5

C OUTPUT "Paid"

D RETURN H

E ENDFUNCTION

Question 5

A FUNCTION Dbl(N) RETURNS INTEGER

B Answer ← N * 2

C RETURNS Answer

D ENDFUNCTION

E OUTPUT Dbl(4)

Answer Key

The RETURN statement

Section A: Quick Questions

B — RETURN Total

A — RETURN Number1 * Number1

B — As the last statement, just before ENDFUNCTION

A — The value currently stored in the variable Result

A — It returns 10 and "Done" is never output

Section B: Match the Pairs

RETURN Number1 * Number1 → Works out the square of Number1 and sends that value back to where the function was called

RETURN Total → Sends the value stored in the variable Total back to the place where the function was called

A function ends with RETURN as its last statement, sending back its answer → FUNCTION Double(Num : INTEGER) RETURNS INTEGER RETURN Num * 2 ENDFUNCTION

RETURN ends the function, so any statement written after it in the same path never runs → RETURN Result OUTPUT "Done"

FUNCTION Square(Number1 : INTEGER) RETURNS INTEGER OUTPUT Number1 * Number1 ENDFUNCTION → The function uses OUTPUT instead of RETURN, so no value is sent back to the caller. It should be RETURN Number1 * Number1.

FUNCTION Add(A : INTEGER, B : INTEGER) RETURNS INTEGER RETURN ENDFUNCTION → RETURN has no value or expression after it, so nothing is sent back. It should be RETURN A + B.

Section C: Definitions

RETURN — RETURN followed by a value or expression sends that value back to where the function was called, e.g. RETURN Number1 * Number1. It also ends the function.

Section D: Fill in the Blanks

FUNCTION Sq(Number1 : REAL) RETURNS REAL
   RETURN Number1 * Number1
ENDFUNCTION

FUNCTION Sq(Number1 : REAL) RETURNS REAL
   RETURN Number1 * Number1
ENDFUNCTION

   Sum ← A + B
   RETURN Sum
ENDFUNCTION

Result ← Sq(5)
OUTPUT Result

FUNCTION Pass(Mark : INTEGER) RETURNS BOOLEAN
   RETURN Mark >= 50
ENDFUNCTION

Section E: Spot the Error

C — RETURN must be followed by a value or expression. A bare RETURN sends nothing back to the call. It should be RETURN Result.

B — OUTPUT only displays the value. It does not send it back to where the function was called, so Sq(5) has no value. The line should be RETURN N * N.

A — Only a function can use RETURN to send a value back. A procedure does not return a value. The header should be FUNCTION Half(N) RETURNS REAL.

D — This returns the hours, not the pay that was worked out. The line should be RETURN Total so the calculated value goes back to the call.

C — RETURNS belongs in the function header to give the data type. Inside the function the statement is RETURN Answer.