Simple character validation.

Debit card

Try

Watch this video to learn about the new concepts shown in the program:

Knowledge organiser

The new commands used in this program and others that may be useful. Select them below to learn more:

x = len(y)

x is assigned to be the number of characters in string. Can also be used to return the number of items in an array/list.

x.isupper()

Returns True if string x is in upper case or False if not.

x.islower()

Returns True if string x is in lower case or False if not.

x.isalpha()

Returns True if string x only contains alphabet letters a-z or A-Z.

x.isdigit()

Returns True if string x only contains numbers 0-9.

x.isalnum()

Returns True if string x only contains alphabet letters or numbers.

x = y.lower()

x is assigned to be the lower case of y.

x = y.upper()

x is assigned to be the upper case of y (capital letters).

Investigate

Questions to think about with this program to check your understanding:

Item question

Identify the Boolean variable used to flag if a character is not a number.

Reveal answer

valid is a Boolean variable used to flag if a character is not a number.

Structure question

State what data type is before the dot in character.isdigit() in line 11.

Reveal answer

“character” is a string data type, it just happens to only contain one character. Some languages support a character data type.

Make

Change the program so that it:

  1. Asks the user to enter their name before their card number.
  2. Has an additional function called validate_name to check whether the name only contains alphabet characters or spaces and outputs the name in upper case.

Typical inputs and outputs from the program would be:

Enter the name on the card: john smith
Enter the 16 digit number: 1234 1234 1234 1234
JOHN SMITH
Card details valid.

Enter the name on the card: invalidname2342
Enter the name on the card: j@hn sm!th
Enter the name on the card: john smith
Enter the 16 digit number: 1234 1234 1234 1234
JOHN SMITH
Card details valid.
🆘 If you're really stuck, use this Parsons code sorting exercise
validate_number
# Function to validate the number is numbers only
def validate_number(number_on_card):
---
    valid = True
    number_of_characters = len(number_on_card)
---
    # Must be 16 (without spaces) or 19 characters (with spaces)
    if number_of_characters == 16 or number_of_characters == 19:
---
        # Check each character in the number
        for character in number_on_card:
---
            # Anything other that a digit and space is invalid
            if not character.isdigit() and character != " ":
---
                valid = False
---
    else:
---
        valid = False
---
    return valid
validate_name
# Function to validate the name is letters and space only
def validate_name(name_on_card):
---
    valid = True
---
    # Check each character in the name
    for character in name_on_card:
---
        # Anything other than an alphanumeric or a space is invalid
        if not character.isalpha() and character != " ":
---
            valid = False
---
    return valid
input_card_details
# Input valid name and number for a debit card (not using check digits)
def input_card_details():
---
    valid_card = False
---
    # Only progress if the name is valid
    while not valid_card:
---
        name_input = input("Enter the name on the card: ")
---
        valid_card = validate_name(name_input)
---
    valid_card = False
---
    # Only progress if the number on the card is valid
    while not valid_card:
---
        number_input = input("Enter the 16 digit number: ")
---
        valid_card = validate_number(number_input)
---
    print(name_input.upper())