Parse File Size string

parseSize.cs

private long ParseSize(string size)
{
	string factor = "KMGTPEZY";

	if (Regex.IsMatch(size, @"^\d+$"))
	{
		return long.Parse(size);
	}
	else
	{
		Match match = Regex.Match(size, @"^(\d+)([KMGTE]?)B?$");
		if (match.Success)
		{
			if (match.Groups[2].Value == string.Empty)
			{
				return long.Parse(match.Groups[1].Value);
			}
			else
			{
				return long.Parse(match.Groups[1].Value) << (10 * (factor.IndexOf(match.Groups[2].Value) + 1));
			}
		}
		else
		{
			throw new ArgumentException("Size format invalid.");
		}
	}
}