I want to know that in particular string1 for which substring of the string1 the string2 matches.Like

String str1="Order Number Order Time Trade Number";

String str2="Order Tm";

string regex = Regex.Escape(str2.Replace(@"\ ", @"\s*");
bool isColumnNameMatched = Regex.IsMatch(str1, regex, RegexOptions.IgnoreCase);

I am using regex because "Order Tm" will also matches "Order Time".It gives bool value that matches occurred or not.

But if it str2 is in str1 then I want to know at which position in the str1 the str2 matches. Like str2="Order Tm" then something like that returns the string which is matched with str2 in the str1.Here str2="Order Tm" then it should return like in the str1,Order Time is the substring where matches is occurred.