Computer Science · Oct / Nov 2025 · Paper 22 · Question 4

To check that the data entered has the required number of characters.

One mark per mark point, max six

MP1

Initialisation of variables – start location for checking and flag, if used

MP2

Input of email address into appropriate variable

MP3

Working condition-controlled loop present

MP4

Correct use of SUBSTRING

MP5

Use of condition for checking value extracted from SUBSTRING / '@'

MP6

Appropriate action if '@' found – loop termination

MP7

Appropriate action if '@' NOT found – check the next character and loop termination if no more characters MP8

Output that only shows when the email address is valid or invalid. Both cases required.

Example:

// Variable declarations are not required

INPUT EmailAddress

Start ← 1

Valid ← FALSE

REPEAT

IF SUBSTRING(EmailAddress, Start, 1) = '@'

THEN

Valid ← TRUE

ELSE

Start ← Start + 1

ENDIF

UNTIL Start > LENGTH(EmailAddress) OR Valid

IF Valid

THEN

OUTPUT EmailAddress, " is valid"

ELSE

OUTPUT EmailAddress, " is NOT valid"

ENDIF