How to get the url part in c#?

Original Response:

Converting the string to a Uri object, you can do the following:

//filePath = @"http://s.ion.com/abc/Std/isd/text.txt"

Uri uri = new Uri(filePath);
string output = uri.AbsoluteUri.Remove(uri.AbsoluteUri.Length - uri.Segments.Last().Length - 1); // -1 removes the '/' character at the end

// output = "http://s.ion.com/abc/Std/isd"

*Note: the Last() function is from the System.Linq library. If you are not using this library, you can still obtain the last segment by replacing uri.Segments.Last().Length with uri.Segments[uri.Segments.Length - 1].Length.

Updated Response based on this comment:

//filePath = @"http://s.ion.com/abc/Std/isd/ser/wer/text.txt"

Uri uri = new Uri(filePath);
string output = uri.AbsoluteUri.Remove(uri.AbsoluteUri.Length - uri.Segments.[uri.Segments.Length - 3].Length - 1); 

// uri.Segments.Length - 3 removes the last 3 unrequired "segments"
// -1 removes the '/' character at the end

// output = "http://s.ion.com/abc/Std/isd"

Updated Response based on the last revision:

//filePath = @"http://s.ion.com/abc/Std/isd/wer/we/wed/sa/ser/text.txt"

Uri uri = new Uri(filePath);
string output = uri.AbsoluteUri.Remove(uri.AbsoluteUri.Length - uri.Segments.[uri.Segments.Length - 6].Length - 1); 

// uri.Segments.Length - 6 removes the last 6 unrequired "segments"
// -1 removes the '/' character at the end

// output = "http://s.ion.com/abc/Std/isd"

If those three strings are possible, then you can do a conditional statement to ascertain which string to manipulate.

if (/* string 1 */)
   // see original response
else if (/* string 2 */)
   // see first updated response
else if (/* string 3 */)
   // see second updated response

string filePath = @"http://s.ion.com/abc/Std/isd/text.txt";
int index = filePath.LastIndexOf('/');
string url = filePath.Substring(0, index);

How about a regex

var url = "http://s.ion.com/abc/Std/isd/text.txt";
// or     "http://s.ion.com/abc/Std/isd/wer/we/wed/text.txt"
// or     "http://s.ion.com/abc/Std/isd/wer/we/wed/sa/ser/text.txt"
// or     "s.ion.com/abc/Std/isd/ser/wer/text.txt"

var match = Regex.Match(url, @"^(?:http:\/\/)?(.*isd)(?=\/)");
Console.WriteLine("http://" + match.Groups[1]);

// output: http://s.ion.com/abc/Std/isd

I am not sure on the context but I always try and keep the file name and path separate for later code modification.

string filePath = @"http://s.ion.com/abc/Std/isd";
string filename = "text.txt";

You should always be able to get your path with a Path.GetDirectoryName. If you need other file names it makes the code much cleaner.