Regular Expressions

string b = @"25[0-5]|2[0-4]\d|1?\d?\d"; // longest match first
string n = @"(?:"+b+@")";               // wrap into non captuering group
string w = @"(?:\*|"+b+@")";            // allow * and wrap into non captuering group
string d = @"\.";                       // separating dot
string ip = n+d+w+d+w+d+w;              // the whole ip = b.(*|b).(*|b).(*|b)

Peter_in_2780 wrote:

Inside the square brackets, the fullstop is not a wildcard.

string replaced = Regex.Replace(all, @"\\begin\{verbatimtab\}.*\\end\{verbatimtab\}", (Match m) => (m.Value), RegexOptions.Singleline);

string p = @"\\begin\{verbatimtab\}[\s\S]*?\\end\{verbatimtab\}";
Console.WriteLine("{0}", Regex.Match(str1, p).Success);

1. use [\s\S] to match any character, independent of singleline or multiline setting
2. use lazy match *? to allow multiple such groups to be matched individually

string pattern = @"\s*(""[^""]*""|\S+)\s*";
var fields = Regex.Matches(input, pattern).Cast<Match>().Select(m=>m.Groups[1].Value);

1. ..."[^"]*"...: "..."
2. ...[^"]*"[^"]*"...: any number of non-"-char, followed by "..." from 1. above
3. ...(?:[^"]*"[^"]*")*...: any repetition of the group described in 2. above
4. ...^(?:...)*...: 3. above must match from the beginning of the text
5. ...^(?:...)*[^"]*...: 4. above, followed by any number of non-"-char
6. (?<=...) : match a space that is preceeded by the expression from 5. above; the (?<=...) is not part of the match

string pattern = @"\s*(""[^""]*""|\S+)\s*"; // maybe a more sophisticated pattern is
                                            // needed since the above expression seems
                                            // to match more,
                                            // but this is maybe an undesired side
                                            // effect of the complicated expression
string[] split = Regex.Matches(input, pattern).Cast<Match>().Select(m=>m.Groups[1].Value).ToArray();