Question

I have to search for the first match of any string in an string array in a textbox starting from a certain position. Like if I have this string array:

string[] s = { "RTS", "RTL" };

And this code:

LDA #$43
STA $1000,x
CMP $00
BEQ .main
.return
RTS
.main
add $01
RTL

It should return RTS since that’s the first match (not the RTL). How can I do this? Additionally, would there be a better way of doing this rather than using an array?

Edited since I gave a bad example of what I was trying to do.

Answer 1

There may be algorithms to do this efficiently, but I don’t know of any. Fortunately this can be represented easily in code through basic searching.

var str = textbox.Text;
var words = new[] { "RTS", "RTL" };
var result = words.AsParallel()
                  .Select(Word => new { Word, Index = str.IndexOf(Word) })
                  .Where(p => p.Index >= 0)
                  .OrderBy(p => p.Index)
                  .Select(p => p.Word)
                  .FirstOrDefault();
if (result == null)
{
    // no match
}
else
{
    // match
}

This should be able to run in parallel fine. If not, remove AsParallel().

---

An alternative approach is to iterate through the string checking for the words picking the first that occurs. It should perform better than the first.

var result = Enumerable.Range(0, str.Length)
                       .SelectMany(i => words.Where(w => str.Substring(i)
                                                            .StartsWith(w)))
                       .FirstOrDefault();

---

If you’d want the best in terms of efficiency, you’d have to write up a state machine for this but would be very complicated for a simple search of 2 (or more) words.