From your post I must make some assumptions - see code below.
As VJ Reddy already suggests in Solution #4, use
Contains(...)
. I would suggest to also check case insensitive:
1 List<string> macIds = new List<string>
2 {
3 "001CCO334550",
4 "001CCO334551",
5 "001CCO334552",
6 "001CCO334553",
7 "001CCO334554",
8 "001CCO334555",
9 "001CCO334556",
10 };
11
12 string mac = "001ccO334554";
13 bool found = macIds.Contains(mac, StringComparer.InvariantCultureIgnoreCase);
14 Console.WriteLine("{0} {1}found", mac, found ? "" : "not ");
Output:
001ccO334554 found
Cheers
Andi