Question

I have a dictionary defined as Dictionary<int, Regex>. There are a number of compiled Regex objects within this. This was done using C# .NET 4.

I’m trying to use a Linq statement to parse the dictionary and return an object that contains all of the dictionary Keys and the index of where each Regex was found in the specified text.

The IDs return fine, but I’m unsure of how to get the location of where the text was found. Can someone help me out?

var results = MyDictionary
    .Where(x => x.Value.IsMatch(text))
    .Select(y => new MyReturnObject()
        {
            ID = y.Key,
            Index = ???
        });

Answer 1

Use the Index property of the Match class instead of doing simple IsMatch.

---

Example:

void Main()
{
    var MyDictionary = new Dictionary<int, Regex>() 
    {
        {1, new Regex("Bar")},
        {2, new Regex("nothing")},
        {3, new Regex("r")}
    };
    var text = "FooBar";

    var results = from kvp in MyDictionary
                  let match = kvp.Value.Match(text)
                  where match.Success
                  select new 
                  {
                        ID = kvp.Key,
                        Index = match.Index
                  };

    results.Dump(); 
}

---

Result