Validation & Verification (Cambridge (CIE) O Level Computer Science)

OUTPUT “Enter a number between 0 and 100”

REPEAT

INPUT Number

IF Number < 0 OR Number > 100 

   THEN

OUTPUT “Number is not between 0 and 100, please try again”

ENDIF

UNTIL Number >= 0 AND Number <= 100

age = int(input("Enter your age"))

while age < 0 or age > 110:
    age = int(input("Enter your age, ensure it is between 0-110"))

OUTPUT “Please enter your 4 digit bank PIN number”

REPEAT

INPUT Pin

IF LENGTH(Pin) <> 4 

THEN

OUTPUT “Your pin number must be four characters in length, please try again”

ENDIF

UNTIL LENGTH(Pin) ← 4

password_length = len(password)

while password_length < 8:
   password = input("Enter a password which is 8 or more characters")

OUTPUT “Enter an integer number”

REPEAT

INPUT Number

IF Number <> DIV(Number, 1)

  THEN

OUTPUT “Not a whole number, please try again”

ENDIF

UNTIL Number ← DIV(Number , 1)

age = input("Enter your age")

while age.isdigit() == False:
    print("enter a number")
    age = input("Enter your age as a number")

OUTPUT “Enter your username”

REPEAT

INPUT Username

IF Username = “” 

THEN

OUTPUT “No username entered, please try again”

ENDIF

UNTIL Username <> “”

name = input("Enter your name")

while name == "":
     name = input("You must enter your name here")

INPUT IDNumber

IF LENGTH(IDNumber) <> 6

THEN

OUTPUT “ID number must be 6 characters long”

END IF

ValidChars ← “ABCDEFGHIJKLMNOPQRSTUVWXYZ”

FirstChar ← SUBSTRING(IDNumber, 1, 1)

ValidChar ← False

Index ← 1

WHILE Index <= LENGTH(ValidChars) AND ValidChar = False DO

IF FirstChar = ValidChars[Index] 

  THEN

ValidChar ← True

ENDIF

Index ← Index + 1

ENDWHILE

IF ValidChar = False

THEN

OUTPUT “First character is not a valid uppercase alphabetical character”

ENDIF

SecondChar ← SUBSTRING(IDNumber, 2, 2)

ValidChar ← False

Index ← 1

WHILE Index <= LENGTH(ValidChars) AND ValidChar = False DO

IF SecondChar = ValidChars[Index] 

  THEN

ValidChar ← True

ENDIF

Index ← Index + 1

ENDWHILE

IF ValidChar = False

THEN

OUTPUT “Second character is not a valid uppercase alphabetical character”

ENDIF

Digits ← INT(SUBSTRING(IDNumber, 3, 6))

IF Digits < 0000 OR Digits > 9999

THEN

OUTPUT “Digits invalid. Enter four valid digits in the range 0000-9999”

ENDIF

Explanation

• The first two characters are checked against a list of approved characters

• The first character is compared one at a time to each valid character in the ValidChars array

• If it finds a match it stops looping and sets ValidChar to True

• The second character is then compared one at a time to each valid character in the ValidChars array

• If it finds a match then it also stops looping and sets ValidChar to True

• Casting is used on the digits to turn the digit characters into numbers

• Once the digits are considered a proper integer they can be checked to see if they are in the appropriate range of 0-9999

• If any of these checks fail then an appropriate message is output

email = input("Enter your email address")
while "@" not in email or "." not in email:
    email = input("Please enter a valid email address")

REPEAT

OUTPUT “Enter your password”

INPUT Password

OUTPUT “Please confirm your password”

INPUT ConfirmPassword

IF Password <> ConfirmPassword 

THEN

OUTPUT “Passwords do not match, please try again”

ENDIF

UNTIL Password ← ConfirmPassword

REPEAT

OUTPUT “Enter your name”

INPUT Name

OUTPUT “Your name is: “, Name, “. Is this correct? (y/n)”

INPUT Answer

UNTIL Answer ← “y”