[C#] RegEx search for two pattern strings and cut what's between

Question

I'm trying to write a little SQL Helper. I have a query like this stored in a string:

DECLARE @V1 INT

--ignore
DECLARE @V11 INT
DECLARE @V12 INT
--endignore

DECLARE @V2 INT

--ignore
SELECT * FROM SampleTable
INNER JOIN AnotherSampleTable
......
--endignore

SELECT * From Employee ORDER BY LastName

My helper method should cut everything what's between

--ignore

and

--endignore

The result string should look like:

DECLARE @V1 INT

DECLARE @V2 INT


SELECT * From Employee ORDER BY LastName

How can achieve my result with RegEx?

Answer 1

Match your string agains "--ignore.+--endignore" and use string.replace to replace it with string.empty.

Answer 2

Here's a short example:

using System;
using System.Text.RegularExpressions;

class Test
{
    static void Main(string[] args)
    {
        string x = @"
A
--ignore
B
--endignore
C";
        Regex regex = new Regex("\r\n--ignore.*?\r\n--endignore\r\n", 
                                RegexOptions.Singleline);
        string y = regex.Replace(x, "\r\n");
        Console.WriteLine(y);
    }
}

Note the use of RegexOptions.Singleline so that . matches any character including \n.

I've used Windows line separators here, but you could make the carriage returns optional if you want to be able to cope with Unix separators. I wanted to make sure that the tokens were on their own lines to avoid any rogue references within the SQL, even if that's very unlikely.