Find whether a extra string is there or not

You can try this code. If this returns true then there are no extra string. Here str is a varible which has a string that needs to be verified.

str.Replace("Var_str",string.Empty)==string.Empty

Try this

const string s = "Var_str_Value";
          var result = s.Replace("Var_str","");
          if(result.Trim().Length>0)
          {
              //Contain more than characters
          }

Hope this helps

From the kind of the question I also get the feeling that the poster wanted to implement something like a tokenizer and his expectation might me along these lines, e.g. if the Val_Str is followed by a whitespace, it is considered as being the first string by it self.

This code would look more like this:

var str = "whatever";
var firstString = "Var_str";
if( str.StartWith(firstString) )
{
    if(str.Length == firstString.Length) { // contains only Var_Str }
    else {
        if( Char.IsWhiteSpace(str, firstString.Length)
        { // A whitespace follows, the first string is separated from the rest
        } else { // immediately followed by some other text
    }
}
else { // does not contain Var_Str at all
}

However this is just a guess on the requirements of the question, so some more details on the expected behavior provided by the poster would be helpful.

var str = "whatever";
var firstString = "Var_str";
if( str.StartWith(firstString))
{
  if(str.Length == firstString.Length)
  {
    // contains only str
  }
  else {
     // also contains something else
  }
}
else{ // contains something else that is not starts with str }