使用连字符作为正则表达式的字符串

Question

I have developed a regex in c# which checks a specific pattern in a log file..

string looks something like this :

05-20-2013 15:57:09.334715 [del1-dhp-26330] Read 100 entries from syslog file test

and my regex function is

\d\d-\d\d-\d\d\d\d \d\d:\d\d:\d\d.\d\d\d\d\d\d [@"+agentName+"]"+" Read 100 entries from "+flatFileLogSourceName;

where agent name and flatfilelogsource name will retrieve me the respective values in the string.

but am getting an error says [xy] range in reverse order.. which should be because of the agent name as it contains hyphen.

so I am basically looking for a method which could escape hyphen as a string like @ does to \\

Answer 1

For the error message that you recibe, I think "[@"+agentName+"]" should be writen as "\\[@"+agentName+"\\]" like in most regular expression flavors, although I don't know the implementation of C#.

Quick explanation

The square brackets forms a class, a kind of collection of valid characters for to match. Those classes can use ranges as [0-9] for matching numbers in decimal notation or [0-7] to match them in octal notation. And to match series of characters like [ae] which match a, b, c, d or e. But ranges can't go in reverse order. So [az] is a valid range but [za] is not. To avoid creating a character class, you must escape the square brackets with a backslask

Answer 2

\\ is the regex escape character.

This should work:

"\d{2}\-\d{2}\-\d{4} \d{2}:\d{2}:\d{2}\.\d{6} \["+agentName+"\] Read 100 entries from "+flatFileLogSourceName

Edit: Although seeing this sentence confuses me as to what you are actually asking for:

where agent name and flatfilelogsource name will retrieve me the respective values in the string.

If you're trying to pull data out of the regex match, this should help you: http://www.regular-expressions.info/named.html