validation - usa and canada zipcode

just check to see if:

1) is 6 characters long
2) if the 1,3,5 characters are letters and if the 2,4,6 characters are numbers

you can check to see if a character is a letter by:

string postalCode = "V5L3T2";

if(postalCode[0] >= "a" && postalCode[0] <= "z")

you can do that for every character.  Note that for numbers if would be >= "0" and <= "9"

i guess there is validation control in asp.net called regular expression can't i use that?

yeah, you can use that.  It just requires you to say what the expression format should be.  That would be a good idea to use if this is for form validation.

here is a link if you want to use a regular expression and don't know how:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconCOMRegularExpressions.asp

does not help the link

i try giving this on page_load


        If Me.ddlCountry.SelectedItem.Text = "USA" Then
            Me.regexpValidator_PostalCode.ValidationExpression = "\d{5}(-\d{4})?"
        ElseIf Me.ddlCountry.SelectedItem.Text = "Canada" Then
            Me.regexpValidator_PostalCode.ValidationExpression = "[A-Z]\d[A-Z]\s\d[A-Z]\d"
        End If

but it does not work

how should i use, based on the user selection usa or canada the validaitonexpression should be assign and only check the validation of which country the user selected.

Expression:  ^\d{5}-\d{4}|\d{5}|[A-Z]\d[A-Z] \d[A-Z]\d$
 
 
Sample Matches:  
44240|||44240-5555|||G3H 6A3
Sample Non-Matches:  
Ohio|||abc|||g3h6a3
Description:  This expression matches three different formats of postal codes: 5 digit US ZIP code, 5 digit US ZIP code + 4, and 6 digit alphanumeric Canadian Postal Code. The first one must be 5 numeric digits. The ZIP+4 must be 5 numeric digits, a hyphen, and then 4 numeric digits. The Canadian postal code must be of the form ANA NAN where A is any uppercase alphabetic character and N is a numeric digit from 0 to 9.

its not working... if i type the candian postal code still getting error