check if a string has special characters..If yes replace them with space else ignore

The first improvement you could make is to get rid of that completely.
If the string does not contain the char value 255, then dr("name") will always contain parts(0) and (presumably) the revised strName value will be discarded - because the final value in the loop determines the value of the array element.
So I assume that is not what you are trying to do...

What are you trying to achieve?
The reason I ask is that unicode characters (which is what strings are made up of) are not necessarily just in the range 0..255 If you are after printable characters only then it's relatively simple - but I would probably use a Regex


"I dont want to declare the special characters. I shud use ch(x) where x=126 to 255 ...I want to basically check for the special characters in a string. If found replace them with a space else i want to store the string in my datarow dr."

What about the special characters below space? Don't you want to get rid of them too?
Can I suggest that you start with a list of *permitted* characters and use a regex to replace all the characters which aren't on it? It's a simpler solution:

Public Dim regex As Regex = New Regex("[^\w\.\,!""$%^&*\(\)-_+=::@']")


' This is the replacement string
Public Dim regexReplace As String = " "


' Replace the matched text in the InputText using the replacement pattern
Dim result As String = regex.Replace(InputText,regexReplace)

There is lot of better way,

trivial code snippet,

import your namespace,

Imports System.Text.RegularExpressions

write your own function,

Public Shared Function RemoveSpecialCharacters(ByVal input As String) As String
       Dim r As New Regex("(?:[^a-z0-9 ]|(?<=['""])s)", RegexOptions.IgnoreCase Or RegexOptions.CultureInvariant Or RegexOptions.Compiled)
       Return r.Replace(input, [String].Empty)
   End Function

usage:

MsgBox("Result :" & RemoveSpecialCharacters("C# language"))

regards
sarva

First of all, the purpose itself is quite questionable. Please see my comment to the question.

Indeed, your code is utterly ineffective. You don't see to understand that the type string is immutable. The method string.Replace does not actually modify any string as this is impossible. Instead, it creates a brand new string each time you call it, and initialize this new string with a modified copy of original string. You assignment simply abandons old reference to string data, and it is eventually garbage-collected. Enormously wasteful. And you make it even worse by iterating by character range (weird concept of "special") and repeating search every time. You would have to through out search and iterate by string's characters instead. But don't do it. You should never use even Replace in a cycle.

Instead, you should use mutable type System.Text.StringBuilder:
http://msdn.microsoft.com/en-us/library/system.text.stringbuilder.aspx[^].

You need to start with empty instance of System.Text.StringBuilder and append some characters just ignoring some others. Note that System.Text.StringBuilder.ToStrings will give you the resulting string.

Through out all your code, try again.

—SA