Question

There are two strings.

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

String str2="Order Tm"; Then I want to know that str2 matches with which substring in the str1.

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.

Like str2="Order Tm" then it should return like in the str1,Order Time is the substring where matches is occurred.

Answer 1

Your question is very unclear and your code does not compile.
There are some problems:

1. You replace "\ " with @"\s*" – but you should replace just " " without \
2. You can’t use Regex.Escape() this way. It will double your \ and result in another regex which is not working. For instance your \s* will become \\s*
3. It seems that you want to match only one word (that’s where your question is unclear). In this case you should match against something like "Order|Tm"
4. To get the matched word you need a grouping construct:

Example:

var str1 = "Order Number Order Time Trade Number";
var str2 = "(Order|Tm)";
string regex = str2.Replace( @" ", @"\s*" );
var match = Regex.Match( str1, regex );

match.Success; // results in "true"
match.Value; // results in "Order"