Converting a boolean array into a string using c#

Question

I have an array that looks something like:

status[0] = true
status[1] = true
status[2] = false
status[3] = true

In reality it's larger but still less than 20. I need to convert this into "ABD". Where each true represents an ordered letter in the alphabet. Can anyone think of an easy really efficient way to do this?

Answer 1

My napkin says this might work...

StringBuilder sb = new StringBuilder();
for(int i = 0; i < status.Length; i++)
{
   if(status[i])
   {
       sb.Append((char)('A' + i));
   }
}

string result = sb.ToString();

Answer 2

string input = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

string result = new String(input.ToCharArray()
                      .Take(status.Length)
                      .Where((c, i) => status[i]).ToArray());