Count Items in an array

[joefox]

I was trying to make a text box, where i can put say 10 digit numbers 2423423434343

then i will have a class that will count the numbers in the text box, and put *** for all the number except the last 4.

Im not sure how to count the numbers that are entered, then loop through them.

any ideas?

namespace Arrays
{
    public class CreditCard
    {
        public static int cardDisplay(int cc)
        {
            int[] card = new int[cc];
            
        }
    }
}

[joefox]

better idea, i think insted of doing an array is there a way to figure out how long a text box is? so if someone enters 23543343 it will count how many numbers are there 8, then take those numbers, and make it so the last 4 only show, and the rest are ****************8

[timeshifter]

For a text box (or any string)

string myStr = "bleh";
MessageBox.Show(myStr.Length.ToString());

For an array:

string[] myStr = { "hi", "bye", "never" };
MessageBox.Show(myStr.Length.ToString());

That should be string[] for the second one... doesn't seem to like that character..

[joefox]

Thanks timeshifer for the info...

now i have a text box on my default.aspx page, and i made a class called displaycard info, with a function that takes the textbox paramater and counts it, then somehow it needs to return the same number entered but only have the last 4 show so if i enter 44455556666, it should kick back ****-****-****-6666

anyideas?

[timeshifter]

Easy. Find the length of the text box, store it as an int. Find the last four characters of the text box, save it as a string. Send back (length-4) stars, + string.

[joefox]

lol easier said then done

[joefox]

this is what i have,but cant get it to work, i just wanted to pass in the number that was entered into the text box, then have it run through this class, and have the class kick out the number **** etc how i stated above..

namespace Arrays
{
    public class CreditCard
    {
        public static int cardlenght;

        public static int cardDisplay(int cc)
        {
            string myStr = Convert.ToString(cc);
            cardlenght = myStr.Length.ToString();

            return cc;
        }
    }
}

[timeshifter]

I'm assuming this is getting called through a button event of some kind...

Regardless. YOu have the length of the string. You want to mask all but the last four digits. So, just run a simple for loop for the length - 4 and build a string with a * per loop.

[joefox]

yes, i have it in a button click

        protected void Button1_Click(object sender, EventArgs e)
        {
            int cc = Convert.ToInt32(TextBox1.Text);

            TextBox2.Text = CreditCard.cardDisplay(cc).ToString();

            Label2.Text = CreditCard.cardlenght.ToString();
        }

sorry for my stupidness, but i have no idea how to loop through and return -4 lol

[timeshifter]

You don't need to convert it to an int, since you're treating it like a string. Check out MSDN online for the structure of a for loop, and see how far you can get with it.

[joefox]

i looked still cant figure it out

namespace Arrays
{
    public class CreditCard
    {
        public static string cardlast4;

        public static int cardDisplay(int cc)
        {
            string myStr = Convert.ToString(cc);
            cardlast4 = myStr.Substring(myStr.Length,-4);

            return cc;
        }
    }
}

[Kasracer]

Change

cardlast4 = myStr.Substring(myStr.Length,-4);

To

cardlast4 = myStr.Substring(myStr.Length -4, 4);

The MSDN is a valuable tool.

I'm sorry if this comes off as rude but if you're not sure on simple string manipulation, how do I know you're going to keep my credit card information secure? Sorry but I wouldn't trust any eCommerce applications you write until you're more seasoned.

[joefox]

so how do i add *** for the begiign now?

        public static string cardLast4(string cc)
        {
            string last4;
            last4 = cc.Substring(cc.Length - 4, 4);

            return last4;
        }

[joefox]

k got it

how to i error check this

        public static string cardLast4(string cc)
        {
            string last4;
            last4 = "********" + cc.Substring(cc.Length - 4, 4);

            return last4;
        }
    }

[timeshifter]

Does that work?

[joefox]

yeah what i have above works perfectly, but i want to check for errors now

[timeshifter]

You have to be a bit more clear than that. You're asking for error checking help, but if the code works, then there are no errors...

[joefox]

i wanted to throw an error if its less then 4 in lenght

[timeshifter]

So why not just use a simple if() check to find out?

[joefox]

i did this

        public static string GetHiddenCreditCardNumber(string creditCard)
        {
            string last4;

            if (creditCard.Length > 4)
            {
                last4 = "********" + creditCard.Substring(creditCard.Length -4);
                return last4;
            }
            else
            {
                return creditCard;
            }
        }

[timeshifter]

I do hope you've been noticing how simple this code really is. Taking it the rest of the way shouldn't be hard for you.

[mendhak]

Shouldn't you throw new Exception in the else {} block as you said?

Also, you said if it's less than 4 in length, so your if statement should have > 3 or >= 4, not >4.