C# Regex Validation

Question

Can someone please validate this for me (newbie of regex match cons).
Rather than asking the question, I am writing this:

Regex rgx = new Regex (@"^{3}[a-zA-Z0-9](\d{5})|{3}[a-zA-Z0-9](\d{9})$"

Can someone telll me if it's OK...

The accounts I am trying to match are either of:

1. BAA89345  (8 chars)
2. 12345678  (8 chars)
3. 123456789112 (12 chars)

Thanks in advance.

From your examples is not very clear for me which are the rules. Could you explicity explain cases where your regex has to match? — Claudio Redi
– Claudio Redi, Commented Oct 4, 2012 at 19:10
A great tool for testing regex is regex fiddle: refiddle.com — Adam Plocher
– Adam Plocher, Commented Oct 4, 2012 at 19:14
I'll put my vote in for RadSoft Regular Expression Designer. radsoftware.com.au — Mitch
– Mitch, Commented Oct 4, 2012 at 19:16
if it's irrelivant whether your first example starts with three letters or whether the accounts are just 8 or 12 characters it changes the regex — DRobertE
– DRobertE, Commented Oct 4, 2012 at 19:16
I mean with C# if you just want to make sure the length of the account is 8 or 12 chars... you could just test the string.length == 8 || string.length == 12 and be done — DRobertE
– DRobertE, Commented Oct 4, 2012 at 19:19

System Down · Accepted Answer · 2012-10-04 19:10:55Z

1

You can use a Regex tester. Plenty of free ones online. My Regex Tester is my current favorite.

answered Oct 4, 2012 at 19:10

System Down

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DRobertE · Accepted Answer · 2012-10-04 19:12:12Z

1

Is the value with 3 characters then followed by digits always starting with three... can it start with less than or more than three. What are these mins and max chars prior to the digits if they can be.

answered Oct 4, 2012 at 19:12

DRobertE

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skunkfrukt · Accepted Answer · 2012-10-04 19:13:42Z

1

You need to place your quantifiers after the characters they are supposed to quantify. Also, character classes need to be wrapped in square brackets. This should work:

@"^(?:[a-zA-Z0-9]{3}|\d{3}\d{4})\d{5}$"

There are several good, automated regex testers out there. You may want to check out regexpal.

answered Oct 4, 2012 at 19:13

skunkfrukt

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Mitch · Accepted Answer · 2012-10-04 19:15:20Z

1

Although that may be a perfectly valid match, I would suggest rewriting it as:

^([a-zA-Z]{3}\d{5}|\d{8}|\d{12})$

which requires the string to match one of:

[a-zA-Z]{3}\d{5} three alpha and five numbers
\d{8} 8 digits or
\d{12} twelve digits.

Makes it easier to read, too...

answered Oct 4, 2012 at 19:15

Mitch

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smartcaveman · Accepted Answer · 2012-10-04 19:16:10Z

0

I'm not 100% on your objective, but there are a few problems I can see right off the bat.

When you list the acceptable characters to match, like with a-zA-Z0-9, you need to put it inside brackets, like [a-zA-Z0-9] Using a ^ at the beginning will negate the contained characters, e.g. `[^a-zA-Z0-9]
Word characters can be matched like \w, which is equivalent to [a-zA-Z0-9_].
Quantifiers need to appear at the end of the match expression. So, instead of {3}[a-zA-Z0-9], you would need to write [a-zA-Z0-9]{3} (assuming you want to match three instances of a character that matches [a-zA-Z0-9]

answered Oct 4, 2012 at 19:16

smartcaveman

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