Writing a validated input algorithm in pseudocode

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Quick Questions

Shade in the A or B circle for each question.

1. Which line should come first in a validation algorithm for a variable called Age?

A INPUT Age

B DECLARE Age : INTEGER

2. Which shows the correct order inside a validation loop?

A OUTPUT "Enter age" then INPUT Age

B INPUT Age then OUTPUT "Enter age"

3. A program must accept an age from 1 to 120. Which UNTIL line is correct?

A UNTIL Age >= 1 AND Age <= 120

B UNTIL Age < 1 OR Age > 120

4. Where should the error message be placed in a REPEAT ... UNTIL validation loop?

A After the UNTIL line, so it always runs once at the end

B Inside the loop, in an IF that runs when the check fails

5. Which UNTIL line gives a correct presence check on Name?

A UNTIL Name <> ""

B UNTIL Name = ""

Match the Pairs

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

Left column		Right column
1REPEAT INPUT Age UNTIL Age >= 0 AND Age <= 120		AKeeps asking for input until the value passes a range check between 0 and 120
2UNTIL LENGTH(Password) >= 8		BThere is no error message when the value is rejected, and the variable Age is never declared with DECLARE Age : INTEGER before the loop.
3A validation algorithm must first declare the variable that will store the input		CDECLARE Score : INTEGER
4A presence check loop repeats until the input is not empty		DREPEAT INPUT Name UNTIL Name <> ""
5REPEAT INPUT Mark UNTIL Mark < 0 OR Mark > 100		ELoop exit condition that repeats until the password passes a length check of at least 8 characters
6REPEAT OUTPUT "Enter age" INPUT Age UNTIL Age >= 0 AND Age <= 120		FThe UNTIL condition tests for invalid values, so the loop stops when the mark is wrong. It should be Mark >= 0 AND Mark <= 100.

Definitions

validation loop

Fill in the Blanks

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

_______ Age : INTEGER OUTPUT "Enter your age (1-120)" INPUT Age

DECLARE Age : INTEGER OUTPUT "Enter your age (1-120)" _____ Age

REPEAT INPUT Age UNTIL Age >= 1 ___ Age <= 120

REPEAT INPUT Password UNTIL ______(Password) >= 8

IF Name = "" THEN ______ "Please enter a name" ENDIF

Spot the Error

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

Question 1

A DECLARE Age INTEGER

B REPEAT

C OUTPUT "Enter age (1-99)"

D INPUT Age

E UNTIL Age >= 1 AND Age <= 99

Question 2

A DECLARE Name : STRING

B Repeat

C OUTPUT "Enter your name"

D INPUT Name

E UNTIL Name <> ""

Question 3

A DECLARE Pass : STRING

B REPEAT

C OUTPUT "Enter password"

D READ Pass

E UNTIL LENGTH(Pass) >= 8

Question 4

A DECLARE Mark : INTEGER

B REPEAT

C INPUT "Enter mark (0-10)"

D INPUT Mark

E UNTIL Mark >= 0 AND Mark <= 10

Question 5

A DECLARE Qty : INTEGER

B REPEAT

C OUTPUT Enter quantity

D INPUT Qty

E UNTIL Qty >= 1 AND Qty <= 20

Answer Key

Writing a validated input algorithm in pseudocode

Section A: Quick Questions

B — DECLARE Age : INTEGER

A — OUTPUT "Enter age" then INPUT Age

A — UNTIL Age >= 1 AND Age <= 120

B — Inside the loop, in an IF that runs when the check fails

A — UNTIL Name <> ""

Section B: Match the Pairs

REPEAT INPUT Age UNTIL Age >= 0 AND Age <= 120 → Keeps asking for input until the value passes a range check between 0 and 120

UNTIL LENGTH(Password) >= 8 → Loop exit condition that repeats until the password passes a length check of at least 8 characters

A validation algorithm must first declare the variable that will store the input → DECLARE Score : INTEGER

A presence check loop repeats until the input is not empty → REPEAT INPUT Name UNTIL Name <> ""

REPEAT INPUT Mark UNTIL Mark < 0 OR Mark > 100 → The UNTIL condition tests for invalid values, so the loop stops when the mark is wrong. It should be Mark >= 0 AND Mark <= 100.

REPEAT OUTPUT "Enter age" INPUT Age UNTIL Age >= 0 AND Age <= 120 → There is no error message when the value is rejected, and the variable Age is never declared with DECLARE Age : INTEGER before the loop.

Section C: Definitions

validation loop — DECLARE the variable, OUTPUT a prompt, INPUT the value, OUTPUT an error message if it fails the check, and REPEAT ... UNTIL the value is acceptable.

Section D: Fill in the Blanks

DECLARE Age : INTEGER
OUTPUT "Enter your age (1-120)"
INPUT Age

DECLARE Age : INTEGER
OUTPUT "Enter your age (1-120)"
INPUT Age

REPEAT
  INPUT Age
UNTIL Age >= 1 AND Age <= 120

REPEAT
  INPUT Password
UNTIL LENGTH(Password) >= 8

IF Name = "" THEN
  OUTPUT "Please enter a name"
ENDIF

Section E: Spot the Error

A — A DECLARE statement needs a colon between the identifier and the data type. It should be DECLARE Age : INTEGER.

B — Cambridge pseudocode keywords must be written in capital letters. The loop must start with REPEAT, not Repeat.

D — READ is not a Cambridge pseudocode command. The value must be read with INPUT, so the line should be INPUT Pass.

C — The prompt for the user must be shown with OUTPUT. INPUT is used to store the value in a variable, so the line should be OUTPUT "Enter mark (0-10)".

C — The text of a prompt must be inside double quotes, otherwise it looks like identifiers. The line should be OUTPUT "Enter quantity".