c# - Regex.Escape() unrecognized exception -

i have following code in c#:

string str = @"\hello ali how you? fine? hello , hi"; console.writeline(regex.matches(regex.escape(str), @"\hello").count); 

i following error:

{"parsing \"\hello\" - unrecognized escape sequence \h."}

i need know when \ + (some names) exists in code. have used @ not using escape sequence characters still mentioned error. can not understand why happens!

escape sequences used independently in both strings and regular expressions different meanings. when prefix string literal @ telling compiler interpret string literally without escape sequences. regular expression engine again sees "\h" , tries interpret escape sequence.

basically need apply both string literal @ and regex.escape function make \h interpreted literal both parsers:

console.writeline(regex.matches(str, regex.escape(@"\hello")).count);