Is there an isAlpha function in VB.NET - vb.net

Question

I have a variable to hold an id
Dim empId as String
So the format for a valid ID is:
'the first character should be a letter [A-Z]
'the rest of the string are digits e.g M2895 would be a valid id
I would like to check each of those characters to see if they fit the correct ID
So far, I have come across the isNumeric() function. Is there a similar function in VB.NET to check if a character is a string or alpha character?

Answer 1

You can use RegularExpressions instead of checking each character of your string by hand:
Dim empId as String = "M2895"
If Regex.IsMatch(empId, "^[A-Z]{1}[0-9]+$") Then
Console.WriteLine("Is valid ID")
End If
If you need a function isAlpha you can create this function by using RegularExpressions too:
Private Function isAlpha(ByVal letterChar As String) As Boolean
Return Regex.IsMatch(letterChar, "^[A-Z]{1}$")
End Function
For completion, to support estonian alphabet too, you can use the following:
Dim empId as String = "Š2859"
If Regex.IsMatch(empId, "^[^\W\d_]{1}[0-9]+$") Then
Console.WriteLine("Is valid ID")
End If

Answer 2

You can use functions which works for all Unicode characters
Char.IsLetter Method (String, Int32)
Indicates whether the character at the specified position in a specified string is categorized as a Unicode letter.
Char.IsDigit Method (Char)
Indicates whether the specified Unicode character is categorized as a decimal digit.
So you end up with validation like
Public Function IsValid(id As String)
If Char.IsLetter(id, 0) = False Then
Return False
End If
If id.Skip(1).All(Char.IsDigit) = False Then
Return False
End If
Return True
End Function

Answer 3

Here is my take an isAlpha function, answering the title of this question:
Public Shared Function isAlpha(ByVal s as String) as Boolean
if s is Nothing then return False
For Each c As Char in s
If not Char.IsLetter(c) then return False
Next
return True
End Function
However, to answer the body of the question, here is my mod of #Fabio's answer:
Public Function isMyAlphaCode(id As String) as Boolean
if id is Nothing then return False
if id.length < 2 then return False
If Char.IsLetter(id, 0) Then
Return False
End If
If id.Skip(1).All(Char.IsDigit) Then
Return False
End If
Return True
End Function