using System;
using System.Text.RegularExpressions;
public class Test
{
public static void Main()
{
string myString = "words words words FIRSTPHRASE these words I want SECONDPHRASE but not these words";
string theWordsIWant = Regex.Replace(myString, @"^.*?FIRSTPHRASE\s*(.*?)\s*SECONDPHRASE.*$", "$1");
Console.WriteLine(theWordsIWant);
}
}
dXNpbmcgU3lzdGVtOwp1c2luZyBTeXN0ZW0uVGV4dC5SZWd1bGFyRXhwcmVzc2lvbnM7CgpwdWJsaWMgY2xhc3MgVGVzdAp7CglwdWJsaWMgc3RhdGljIHZvaWQgTWFpbigpCgl7CgkJc3RyaW5nIG15U3RyaW5nID0gIndvcmRzIHdvcmRzIHdvcmRzIEZJUlNUUEhSQVNFIHRoZXNlIHdvcmRzIEkgd2FudCBTRUNPTkRQSFJBU0UgYnV0IG5vdCB0aGVzZSB3b3JkcyI7CgkJc3RyaW5nIHRoZVdvcmRzSVdhbnQgPSBSZWdleC5SZXBsYWNlKG15U3RyaW5nLCBAIl4uKj9GSVJTVFBIUkFTRVxzKiguKj8pXHMqU0VDT05EUEhSQVNFLiokIiwgIiQxIik7CgkJQ29uc29sZS5Xcml0ZUxpbmUodGhlV29yZHNJV2FudCk7Cgl9Cn0=