Length check

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Date:

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Quick Questions

Shade in the A or B circle for each question.

1. Which check makes sure a password has at least 8 characters?

A Length check

B Range check

2. Which condition is a valid length check for a password of at least 8 characters?

A LENGTH(Password) >= 8

B Password >= 8

3. A four-digit PIN must have exactly 4 characters. Which condition accepts only valid PINs?

A LENGTH(PIN) > 4

B LENGTH(PIN) = 4

4. A user enters the PIN 123. Does it pass the length check LENGTH(PIN) = 4?

A No, it has only 3 characters

B Yes, because the digits are all numbers

5. A username must be no more than 12 characters long. Which condition is correct?

A LENGTH(Username) >= 12

B LENGTH(Username) <= 12

Match the Pairs

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

Left column		Right column
1LENGTH(Password) >= 8		ALENGTH(Username) <= 12
2LENGTH(PIN) = 4		BChecks that the password has at least 8 characters (a minimum length check)
3A length check can set a maximum length, so a username must not be longer than 12 characters		CThe function name is written in the wrong case. Keywords and functions must be in capital letters, so it should be LENGTH(PIN).
4A length check can set both a minimum and a maximum, so a username must be 6 to 12 characters		D= tests for exactly 8 characters, so longer passwords are wrongly rejected. A minimum length needs >= 8.
5IF Length(PIN) = 4 THEN		ELENGTH(Username) >= 6 AND LENGTH(Username) <= 12
6IF LENGTH(Password) = 8 THEN		FChecks that the PIN has exactly 4 characters (an exact length check)

Definitions

LENGTH(Password) >= 8

Fill in the Blanks

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

IF ______(Password) >= 8 THEN

IF LENGTH(PIN) _ 4 THEN

IF LENGTH(Password) __ 8 THEN

IF LENGTH(Username) __ 12 THEN

REPEAT INPUT PIN UNTIL LENGTH(PIN) = _

Spot the Error

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

Question 1

A DECLARE Password : INTEGER

B INPUT Password

C IF LENGTH(Password) >= 8 THEN

D OUTPUT "Accepted"

E ENDIF

Question 2

A INPUT PIN

B IF PIN = 4 THEN

C OUTPUT "PIN OK"

D ELSE

E OUTPUT "Must be 4 digits"

F ENDIF

Question 3

A INPUT Password

B WHILE LENGTH(Password) < 8 DO

C OUTPUT Too short

D INPUT Password

E ENDWHILE

Question 4

A INPUT Username

B IF LENGTH(Username) > 12 THEN

C PRINT "Too long"

D ELSE

E OUTPUT "Saved"

F ENDIF

Question 5

A DECLARE PIN STRING

B INPUT PIN

C IF LENGTH(PIN) = 4 THEN

D OUTPUT "Accepted"

E ENDIF

Answer Key

Length check

Section A: Quick Questions

A — Length check

A — LENGTH(Password) >= 8

B — LENGTH(PIN) = 4

A — No, it has only 3 characters

B — LENGTH(Username) <= 12

Section B: Match the Pairs

LENGTH(Password) >= 8 → Checks that the password has at least 8 characters (a minimum length check)

LENGTH(PIN) = 4 → Checks that the PIN has exactly 4 characters (an exact length check)

A length check can set a maximum length, so a username must not be longer than 12 characters → LENGTH(Username) <= 12

A length check can set both a minimum and a maximum, so a username must be 6 to 12 characters → LENGTH(Username) >= 6 AND LENGTH(Username) <= 12

IF Length(PIN) = 4 THEN → The function name is written in the wrong case. Keywords and functions must be in capital letters, so it should be LENGTH(PIN).

IF LENGTH(Password) = 8 THEN → = tests for exactly 8 characters, so longer passwords are wrongly rejected. A minimum length needs >= 8.

Section C: Definitions

LENGTH(Password) >= 8 — A length check tests the number of characters in an input is the required length or within a limit, using LENGTH, e.g. a password of at least 8 characters or a PIN of exactly 4.

Section D: Fill in the Blanks

IF LENGTH(Password) >= 8 THEN

IF LENGTH(PIN) = 4 THEN

IF LENGTH(Password) >= 8 THEN

IF LENGTH(Username) <= 12 THEN

REPEAT
  INPUT PIN
UNTIL LENGTH(PIN) = 4

Section E: Spot the Error

A — A password is text, so it must be declared as STRING. LENGTH counts the characters in a string, so Password cannot be an INTEGER. The line should be DECLARE Password : STRING.

B — A length check must test the number of characters, not the value typed. It should be IF LENGTH(PIN) = 4 THEN, so a PIN such as 1234 passes because it has exactly 4 characters.

C — Text in an OUTPUT statement must be inside double quotes. The line should be OUTPUT "Too short".

C — Cambridge pseudocode uses OUTPUT to display a message, not PRINT. The line should be OUTPUT "Too long".

A — A DECLARE statement needs a colon between the identifier and the data type. The line should be DECLARE PIN : STRING.