Imports System
Imports System.Text
Public Class Test
Public Shared Function convert_part_to_lowercase(s As String, from_idx as Integer, to_idx as Integer) As String
Dim len As Integer = s.Length
If (from_idx < 0 Or to_idx > len) Then
return s
End If
Dim sb As StringBuilder = new StringBuilder(s)
For i As Integer = 0 To len - 1
if ((i >= from_idx And i <= to_idx) And (s(i) >= "A" And s(i) <= "Z")) Then
sb(i) = Char.ToLower(sb(i))
End If
Next
return sb.ToString()
End Function
Public Shared Sub Main()
Dim s As String = "VB.NET PROGRAMMING"
s = convert_part_to_lowercase(s, 3, 6)
Console.WriteLine(s)
s = convert_part_to_lowercase(s, 11, 12)
Console.WriteLine(s)
End Sub
End Class
' run:
'
' VB.net PROGRAMMING
' VB.net PROGraMMING
'
