Question

We have a requirement to display bank routing/account data that is masked with asterisks, except for the last 4 numbers. It seemed simple enough until I found this in unit testing:

string.Format("{0:****1234}",61101234)

is properly displayed as: "****1234"

but

string.Format("{0:****0052}",16000052)

is incorrectly displayed (due to the zeros??): "****1600005252""

If you use the following in C# it works correctly, but I am unable to use this because DevExpress automatically wraps it with “{0: … }” when you set the displayformat without the curly brackets:

string.Format("****0052",16000052)

Can anyone think of a way to get this format to work properly inside curly brackets (with the full 8 digit number passed in)?

UPDATE: The string.format above is only a way of testing the problem I am trying to solve. It is not the finished code. I have to pass to DevExpress a string format inside braces in order for the routing number to be formatted correctly.

Answer 1

I think you are looking for something like this:

string.Format("{0:****0000}", 16000052);

But I have not seen that with the * inline like that. Without knowing better I probably would have done:

string.Format("{0}{1}", "****", str.Substring(str.Length-4, 4);

Or even dropping the format call if I knew the length.

These approaches are worthwhile to look through: Mask out part first 12 characters of string with *?

As you are alluding to in the comments, this should also work:

string.Format("{0:****####}", 16000052);

The difference is using the 0’s will display a zero if no digit is present, # will not. Should be moot in your situation.

If for some reason you want to print the literal zeros, use this:

string.Format("{0:****\0\052}", 16000052);

But note that this is not doing anything with your input at all.