Find all words starts with @@ and ends with @@ in long string

Question

I have a quite big string. In that big string, I want to get all UNIQUE words starts with @@ and ends with @@. Between @@ could be text, number or alphanumeric or anything.

Once I get all the UNIQUE words starting @@ and ends with @@, I want to replace each word with a value which matches a key in a different array.

Looking for the solution in C#.

Answer 1

Try this regex:

@@\b\S+?\b@@

Sample Code:

List<string> lst = new List<string>();
MatchCollection mcol = Regex.Matches(sampleString,@"@@\b\S+?\b@@");

foreach(Match m in mcol)
{
    lst.Add(m.Tostring());
}

Here lst contains matched value(s), compare each value and replace it as per you criteria.

Sample live demo

Answer 2

Try following code (use Regex.Replace Method):

string s = @"@@Welcome@@ to @@reg-ex@@ @@world@@.";
Dictionary<string, string> sub = new Dictionary<string,string>{
    { "@@reg-ex@@", "regular expression" },
    { "@@world@@", "hell" },
};
Regex re = new Regex(@"@@.*?@@");
Console.WriteLine(re.Replace(s, x => {
    string new_x;
    return sub.TryGetValue(x.ToString(), out new_x) ? new_x : x.ToString();
}));

prints:

@@Welcome@@ to regular expression hell.

Answer 3

Example using Regex and Linq

string text = "@@bb@@@@cc@@@@sahasjah@@@@bb@@";
var matches = Regex.Matches(text, @"@@[^@]*@@");
var uniques = matches.Cast<Match>().Select(match => match.Value).ToList().Distinct();