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 = y.Length

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

Char.IsUpper(c)

Returns true if character c is upper case or false if not.

Char.IsLower(c)

Returns true if character c is lower case or false if not.

Char.IsLetter(c)

Returns true if character c is an alphabet letter a-z or A-Z.

Char.IsDigit(c)

Returns true if character c is a digit 0-9.

Char.IsLetterOrDigit(c)

Returns true if character c is an alphabet letter or a digit.

x = y.ToLower()

x is assigned to be the lower case of y.

x = y.ToUpper()

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

Investigate

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

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.

State what data type is before the dot in Char.IsDigit(character).

Reveal answer

“character” is a char data type, the C# type that holds a single character.

Make

Change the program so that it:

Asks the user to enter their name before their card number.
Has an additional function called validate_name to check whether the name only contains alphabet characters or spaces. Once a valid name is entered, it is output in upper case.

Typical inputs and outputs from the program would be:

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

Enter the name on the card:
Enter the 16 digit number:
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
static bool validate_number(string number_on_card)
{
---
    bool valid = true;
    int number_of_characters = number_on_card.Length;
---
    // Must be 16 (without spaces) or 19 characters (with spaces)
    if (number_of_characters == 16 || number_of_characters == 19)
    {
---
        // Check each character in the number
        foreach (char character in number_on_card)
        {
---
            // Anything other that a digit and space is invalid
            if (!Char.IsDigit(character) && character != ' ')
            {
---
                valid = false;
---
            }
---
        }
---
    }
---
    else
    {
---
        valid = false;
---
    }
---
    return valid;
}

`validate_name`

// Function to validate the name is letters and space only
static bool validate_name(string name_on_card)
{
---
    bool valid = true;
---
    // Check each character in the name
    foreach (char character in name_on_card)
    {
---
        // Anything other than a letter or a space is invalid
        if (!Char.IsLetter(character) && character != ' ')
        {
---
            valid = false;
---
        }
---
    }
---
    return valid;
}

`input_card_details`

// Input valid name and number for a debit card (not using check digits)
static void input_card_details()
{
---
    bool valid_card = false;
    string name_input = "";
---
    // Only progress if the name is valid
    while (!valid_card)
    {
---
        Console.WriteLine("Enter the name on the card:");
        name_input = Console.ReadLine();
        valid_card = validate_name(name_input);
---
    }
---
    valid_card = false;
    string number_input = "";
---
    // Only progress if the number on the card is valid
    while (!valid_card)
    {
---
        Console.WriteLine("Enter the 16 digit number:");
        number_input = Console.ReadLine();
        valid_card = validate_number(number_input);
---
    }
---
    Console.WriteLine(name_input.ToUpper());
}