C# :: How To Match Regex If Input Was Array Of Strings

In the MSDN, it gives an example using Regex.Matches method:

using System;
using System.Text.RegularExpressions;
public class Example {
public static void Main() {
string pattern = "a*";
string input = "abaabb";
foreach (Match m in Regex.Matches(input, pattern))
Console.WriteLine("'{0}' found at index {1}.",
m.Value, m.Index);

[code]......

I am wondering if string input was an array of strings instead, how would I use Regex.Matches?

What I was thinking about doing is having the input array set to ToString(), input.ToString(), but that doesn't seem to work.