Split string into string array of single characters

I believe this is what you're looking for:

char[] characters = "this is a test".ToCharArray();

Strings in C# already have a char indexer

string test = "this is a test";
Console.WriteLine(test[0]);

And...

if(test[0] == 't')
  Console.WriteLine("The first letter is 't'");

This works too...

Console.WriteLine("this is a test"[0]);

And this...

foreach (char c in "this is a test")
  Console.WriteLine(c);

EDIT:

I noticed the question was updated with regards to char[] arrays. If you must have a string[] array, here's how you split a string at each character in c#:

string[] test = Regex.Split("this is a test", string.Empty);

foreach (string s in test)
{
  Console.WriteLine(s);
}

Simple!!
one line:

 var res = test.Select(x => new string(x, 1)).ToArray();