A string contains certain characters only - vba

Question

I am new to VBA and Syntax in VBA is not very friendly to me. I'm trying to validate a field which is string type. In that particular field, I want the string contains letters and comma and space only.
This is my current approach:
myArray = Array("a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", " ", ",", "-", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z")
If Not IsInArray(erName.Text, myArray) Then
valid = False
erName.ForeColor = vbRed
End If
And the IsInArray function is like the following:
Public Function IsInArray(stringToBeFound As String, arr As Variant) As Boolean
Dim i
For i = LBound(arr) To UBound(arr)
If arr(i) = stringToBeFound Then
IsInArray = True
Exit Function
End If
Next i
IsInArray = False
End Function
But this is not a very efficient approach because I don't want to loop over the array for every character in the string. Is there a simple way to perform this validation? Any help is appreciated. Thank you.

Answer 1

RegEx solution
Function StringCheck(str)
Set objRegEx = New RegExp
With objRegEx
.IgnoreCase = True
.Global = False
.MultiLine = False
.Pattern = "[a-zA-Z, ]*" 'alphabets + comma + space
End With
Set objMatch = objRegEx.Execute(str)
If objMatch.Count = 1 Then
If Len(str)=Len(objMatch(0).Value) Then 'if len of string matches the regex find
StringCheck = True
Else
StringCheck = False
End If
Else
StringCheck = False
End If
End Function
MsgBox StringCheck("Pankaj Jaju") 'True
MsgBox StringCheck("Pankaj_Jaju") 'False
MsgBox StringCheck("Pankaj,Jaju") 'True
MsgBox StringCheck("Pankaj,Jaju 1234") 'False

Answer 2

You don't have to loop over every character to check whether it lies in your defined array. You just need to check whether the given character is in range of the permitted ASCII values :
ASCII value of character i >= 65 and <=90 (For upper case letters)
OR
ASCII value of character i >= 97 and <= 122 (For lower caase letters)
OR
ASCII value of character i == 44 (For comma)
OR
ASCII value of character i == 32 (For space)
You can define a check for these four conditions to avoid loop.
Public Function IsInArray(stringToBeFound As String) As Boolean
Dim i
For i = 1 to Len(stringToBeFound)
If (stringToBeFound(i) >= 65 and stringToBeFound(i) <= 90) or (stringToBeFound(i) >= 97 and stringToBeFound(i) <= 122) or
(stringToBeFound(i) = 44) or
(stringToBeFound(i) = 32) Then
IsInArray = True
Exit Function
End If
Next i
IsInArray = False
End Function