Formatting a String in C#

I also use Functions / Property to validate data.
Two reasons:

• Regular exprexsions are cryptic, no debugable, No documentable. 
• Functions / Property can raise exceptions especific for each error. 

To develop the validation code, I use states. This simplifies a lot the code.

The sample code is ilustrate the concept.

    'Format: [-][Days{d,Space}][Horas][{h,':'}[Minutos]]
    <DebuggerStepThrough()> _
    Public Shared Function Parse(ByVal Dato As Object) As Int32
        Dim s As String = TryCast(Dato, String) 'Permite DbNull    
        If s Is Nothing Then Return 0
        s = s.Trim
        Dim v, ac, state As Integer, LastCharDigit, Negativo As Boolean
        For n As Integer = 0 To s.Length - 1
           Dim Digit As Integer = CharUnicodeInfo.GetDigitValue(s, n) '-1 si no es dígito
           If Digit >= 0 Then v = v * 10 + Digit : LastCharDigit = True : Continue For
           Select Case Char.ToLower(s(n))
                Case "d"c
                    If state = 0 Then state = 1 : ac = v * 1440 : v = 0 Else Throw New FormatException("Invalid Format - d")
                Case ":"c, "h"c
                    If state < 2 Then state = 2 : ac += v * 60 : v = 0 Else Throw New FormatException("Invalid Format - :")
                Case " "c : If LastCharDigit = False Then Continue For
                            If state > 0 Then Throw New FormatException("Espacio inválido")
                            state = 1 : ac = v * 1440 : v = 0 'Asumo "d"c
                Case "-"c : If n = 0 Then Negativo = True Else Throw New FormatException("Invalid Format - Caracter invalido")
                Case Else : Throw New FormatException("Invalid Format - Caracter invalido")
           End Select
           LastCharDigit = False
        Next
        If state < 2 Then v *= 60 'Por defecto Horas
        ac += v
        Return If(Negativo, -ac, ac)
    End Function
                                              

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The idea of course would be to use the regular expression and string replacement inside a function or property.

Yeah... there are a few things wrong with the code posted above:

1. It's in Spanish 
2. It's in VB 
3. It's in VB 
4. I'm not sure what "concept" is really even being illustrated. 
5. It's in VB. 

Barf.

Author: please be more specific as to your request. What is the purpose of this validation? Do you have any resolution preferenes (eg do you prefer not to use RegEx?)? Let us know.

I want to write a property in C# to test the format of a string called Vcode that is in a constructor, so the user is assigning a string input called Vcode I want to test if this string has a format like the following:

LetterDigitLetterDigitLetterDigit (eg:P6T4K9) and sometimes the user assigns a string with a space between the Letter and the Digit, like LetterDigitLetter DigitLetterdigit (eg: P7Y 8L4) I want to eliminate any space between the letters and the digits in the string and concatenate the whole thing (maybe we can use the Trim Function to eliminate the space in between the characters and the digits. and finally the user might assign a string to the contructor that includes a dash between the letter and the digit, Like LetterDigit-LetterDigitLetterDigit (eg: J8-Y6K5) so I want to eliminate the dashes between the Letter and the digit and concatenate.(maybe also we can use the Trim function). All those scenarios mentioned above are valid input of string and anything else is not valid.

Can anyone help me to do this function in C#?

jamesrh: it can be a function to test the user input  VCODE too.

In other words the string Vcode should have this format: LetterDigitLetterDigitLetterDigit if a dash or a whiteSpace are in between they should be eliminated and then concatenated to have this format LetterDigitLetterDigitLetterDigit. anything else is not Valid.

Please find below what the function should achieve for user string input Vcode:

1. First  It will check if the string input contains whiteSpaces or Dashes
2. if so it should Eliminate the Whitespaces and the Dashes then Concatenate
3. Then it will Check the Length of the string is it is equal to 6 if so it will check the string format if it follows this format LetterDigitLetterDigitLetterDigit  

if all those 3 are true then return errorCode = 0  which is success or Valid

Else

If any of these is wrong  return errorCode = 3. Which is not Valid

Sorry to be a little dense with this, but I want to make sure I am really giving you what you are looking for.  You would like to be use this something like?:

Class1 myClass = new Class1("P6T4K9");
myClass.Vcode = "P7Y 8L4";
string currentVcode = myClass.Vcode;  // currentVcode now = "P7Y8L4"

If this is what you are trying to do, then you need something like the following code:

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;  
 
namespace Test
{
    class Class1
    {
        private string _Vcode;
 
        public string Vcode
        {
            get { return Vcode; }
            set
            {
                if (!Regex.IsMatch(value, @"[A-Za-z]\d[A-Za-z][ -]?\d[A-Za-z]\d"))
                    //we throw an exception because setting a property can't return a value
                    //also when called by the constructor you can't send back a return code
                    throw new Exception("Invalid Vcode format");
 
                _Vcode = value.Replace(" ", "").Replace("-", "");
            }
        }
 
        //for a lot of reasons it is a good idea to have a default constructor
        public Class1()
        { 
            //do any initialization that doesn't depend on parameters
        }
 
        public Class1(string vCode)
        {
            //call it this way to invoke the validation code above.
            this.Vcode = vCode;   
        }
    }
}
                                              

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The code I gave you has a couple of caveats.  1) P6T-4K9 and P6T 4K9 are valid. P6T--4K9, P6T -4K9, P6T  4K9, etc are not.  (I would be a small adjustment to change this if necessary)  2)  You could do everything will Regex and captures, however, I wanted to make the code a simple and straightforward as was practical.  If you want to make the change mentioned in item 1, we would then get rid of the replace and use regex and captures.

Jamesrh:
Thank you for code, I think it is answering my question, but I want to double check on this:

Does this expression:   !Regex.IsMatch(value, @"[A-Za-z]\d[A-Za-z][ -]?\d[A-Za-z]\d"))
 take care of having this sequence of string format Valid:

LetterDigitLetter-DigitLetterDigit (eg:K2H-7A1) should eliminate the - and concatenate
or
LetterDigitLetter DigitLetterDigit (eg: K2H 7A1) should eliminate the whiteSpace and concatenate to be like this LetterdigitLetterDigitLetterDigit (eg:K2H7A1)

and does this expression take care of the length of the string just to be = 6 after concatenation otherwise not valid.

I want just to double check on the above to give you the 500 full points? :))

Jamesrh: Can you please transform everything to a function instead of a property?

The below is the code in function format.  Notice the regular expression is slightly different as my first example did not check for additional characters before and after.  So the regex tests for the following 3 formats for vCode coming in:  M1M1M1, M1M-1M1, M1M 1M1.  Anything else including additional characters before or after the pattern results in return 3.  The replace statement removes the space or dash if there is one.

You would call the code like so:
string testVcode = "K2H-7A1";
if(EvaluateVcode(ref testVcode) != 3)
   //do some stuff
  //at this point testVcode = K2H7A1

public int EvaluateVcode(ref string vCode)
{
  if (!Regex.IsMatch(value, @"^[A-Za-z]\d[A-Za-z][ -]?\d[A-Za-z]\d$"))
     return 3;
 
  vCode = value.Replace(" ", "").Replace("-", "");  
  return 0;   
   
}

                                              

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james:
When I build the project it is complaining about the value, im getting "the name 'value' does not exist in the current context".
I am using this reference below:
using System.Text.RegularExpressions;  


any solution about it?

value was only vaild in the property scenario.