Extract a character at particular place in a string

Question

I have a function:

Private Function getbyte(s As String, ByVal place As Integer) As String
If place < Len(s) Then
place = place + 1
getbyte = Mid(s, place, 1)
Else
getbyte = ""
End If
End Function

For extracting a character at a particular place in a string, how can I shorten this or any alternate for the same purpose?

Answer 1

According to MSDN, this function is already implemented:

' Code from MSDN
'
Dim myString As String = "ABCDE" 
Dim myChar As Char 
' The value of myChar is "D".
myChar = myString.Chars(3)

---

A review of your code

• Please indent your code.
• I would choose another, more meaningful name for your function: getCharAt or getByteFromString. It is now clear that the function operates on a string.
• I would use the clearer parameter name str instead of s.

• "Compress":

  place = place + 1
  getbyte = Mid(s, place, 1)
  
  ' change to
  getbyte = Mid(s, place + 1, 1)
  

  The first version is definitely not wrong or ugly, but why use an extra line if we could express the same logic in the same clear manner?

• You could use If to shorten your code:

  Private Function getbyte(str As String, ByVal place As Integer) As String
    getbyte = If(place < Len(str), Mid(str, place + 1, 1), "")
  End Function
  

Answer 2

First thing's first. Indent the code. Everything inside of Function...End Function should be indented one tab or four spaces. Same thing with code inside the If...End If.

Private Function getbyte(s As String, ByVal place As Integer) As String
    If place < Len(s) Then
        place = place + 1
        getbyte = Mid(s, place, 1)
    Else
        getbyte = ""
    End If
End Function

As for a simpler method for getting a byte at a particular place in a string, I think it's a wash for VB6, but there is an alternative. Create a byte array then return the byte at the index you want to retrieve. How this is done is different in VB6 vs. VB.NET.

VB6

The function to return a byte array in VB6 is StrConv().

Private Function GetByte(ByVal str As String, ByVal place As Integer) as String
    bytes() = StrConv(str, vbFromUnicode)
    GetByte = bytes[place + 1]
End If

I did not implement any checks on the place parameter, but it should check for both place < Len(str) and place > Len(str).

Note that I used ByVal for both parameters. You had only used it for one of them in the code above. By default, references are passed ByRef, so it's good practice to declare it so we know that functions won't have side effects and go changing s on us. Speaking of s, single letter parameter names are the devil in VB6. The IDE isn't smart enough to replace all instances of it like in VB.NET. Try to do a find and replace on "s" and see what happens. Opt for a longer more meaningful name. Even dsmvwlng string to str would be preferable over s.

I think the old VB6 conventions should be dropped in preference of the new VB.NET naming conventions. Methods should be PascalCased. Note that I changed getByte to GetByte.

VB.NET

There is a built in string function to do exactly what your function does. It's called GetChar. MSDN documentation.