Random string generator, based on format

RandomExtensions.cs

void Main()
{
	Random rnd = new Random();
	rnd.GetString("1-###-000").Dump();
}

public static class RandomExtensions
{
	public static string GetString(this Random random, string format)
	{
		// Based on http://stackoverflow.com/questions/1344221/how-can-i-generate-random-alphanumeric-strings-in-c
		// Added logic to specify the format of the random string (# will be random string, 0 will be random numeric, other characters remain)
		StringBuilder result = new StringBuilder();
		for(int formatIndex = 0; formatIndex < format.Length ; formatIndex++)
		{
			switch(format.ToUpper()[formatIndex])
			{
				case '0': result.Append(getRandomNumeric(random)); break;
				case '#': result.Append(getRandomCharacter(random)); break;
				default : result.Append(format[formatIndex]); break;
			}
		}
		return result.ToString();
	}
	
	private static char getRandomCharacter(Random random)
	{
		string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
		return chars[random.Next(chars.Length)];
	}
	
	private static char getRandomNumeric(Random random)
	{
		string nums = "0123456789";
		return nums[random.Next(nums.Length)];
	}
}

This extension method (on Random) allows to generate a random string, in the format of your choice. This was added as a solution on StackOverflow: http://stackoverflow.com/questions/1344221/how-can-i-generate-random-alphanumeric-strings-in-c