I have to get  the 3rd index of '.'(fullstop).I have retrieved the first index but want the third.

Please help.

Something like this:

int index = 0;

string text = "this.is a test.string.to return.3rd one.";

for (int loop = 0; loop 

	index = text.IndexOf('.', index + 1);

 try this

Dim str As String = "ht.tt.po.fd"

Dim cnt = 0

Dim ina = str.IndexOf(".")

cnt = ina

You can use the Split method for this:

string words = "Some.words.here.for.testing";
string word = words.Split('.').ElementAt(2);

Here is another way 

   // using System.Text.RegularExpressions

            string inputString = "The cat saw the other cats playing in the back yard.";

            string pattern = "cat";

            MatchCollection matches = Regex.Matches(inputString, pattern);

            foreach (Match match in matches)

                Response.Write("Value: " + match.Value + ", Index= " + match.Index + "<BR>");