Parsing with Regular Expressions - Counting Leading Spaces in a StringCountSpacesBeforeFirstChar |   | Is there a function to count the number of leading spaces in a line of text? This is a valuable function when parsing and indenting source code. There is not built in function in VB6 or .NET to do this, but the following functions show the VB6 and .NET solution to the problem. In writing add-ins, I do a lot of parsing of source code. I needed a function that would tell me how many spaces there are at the start of a line of text before the first non blank character. In VB6, I wrote the following function to loop through the leading characters and count the spaces.
Public Overloads Function CountSpacesBeforeFirstChar(ByVal psIN As String) _
As Integer
' Count the number of spaces before first
' non space character in a source line
Dim iSpCnt As Integer
For iSpCnt = 0 To Len(psIN) - 1
If Mid$(psIN, iSpCnt + 1, 1) <> " " Then
CountSpacesBeforeFirstChar = iSpCnt
Exit Function
End If
Next iSpCnt
CountSpacesBeforeFirstChar = iSpCnt
End Function
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In .NET, using Regular Expressions is much simpler and potentially faster.
Public Overloads Function CountSpacesBeforeFirstChar(ByVal Source As String) _
As Integer
' Count the number of spaces before first
' non space character in a source line
Return CountSpacesBeforeFirstChar(Source, 0)
End Function
Public Overloads Function CountSpacesBeforeFirstChar(ByVal Source As String, _
ByVal StartAt As Integer) _
As Integer
' Count the number of spaces before first
' non space character in a source line,
' beginning at piST
' since the regex match includes the first non-black char,
' sub 1 from match.length
Return Regex.Match(Source.Substring(StartAt), "^ *[^ ]").Length - 1
End Function
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