/// <summary>
/// Converts a number value into a string that represents the number 
/// expressed in whole kilobytes. This is a format similar to the 
///	Windows Explorer "Size" column.
/// </summary>
public static string FileSizeToStringKB(long fileSize)
{
	return string.Format("{0:n0} KB", Math.Ceiling((double)fileSize / 1024));
}
 
 
/// <summary>
/// Converts a numeric value into a string that represents the number 
///	expressed as a size value in bytes, kilobytes, megabytes, gigabytes, 
///	or terabytes depending on the size. Output is identical to 
///	StrFormatByteSize() in shlwapi.dll. This is a format similar to 
/// the Windows Explorer file Properties page. For example:
///	     532 ->  532 bytes
///     1240 -> 1.21 KB
///	  235606 ->  230 KB
///  5400016 -> 5.14 MB
/// </summary>
/// <remarks>
///	It was surprisingly difficult to emulate the StrFormatByteSize() function
/// due to a few quirks. First, the function only displays three digits:
///  - displays 2 decimal places for values under 10	(e.g. 2.12 KB)
///  - displays 1 decimal place for values under 100	(e.g. 88.2 KB)
///	 - displays 0 decimal places for values under 1000	(e.g. 532 KB)
///	 - jumps to the next unit of measure for values over 1000  (e.g. 0.97 MB)
/// The second quirk: insiginificant digits are truncated rather than 
/// rounded. The original function likely uses integer math.
/// This implementation was tested to 100 TB.
/// </remarks>
public static string FileSizeToString(long fileSize)
{
	double value;
	string unit;
 
	if (fileSize < 1024)
	{
		return string.Format("{0} bytes", fileSize);
	}
	else 
	{
		value = fileSize;
		value = value / 1024;
		unit = "KB";
		if (value >= 1000)
		{
			value = Math.Floor( value );
			value = value / 1024;
			unit = "MB";
		}
		if (value >= 1000)
		{
			value = Math.Floor( value );
			value = value / 1024;
			unit = "GB";
		}
		if (value >= 1000)
		{			value = Math.Floor( value );
			value = value / 1024;
			unit = "TB";
		}
 
		if (value < 10)
		{
			value = Math.Floor( value * 100 ) / 100;
			return string.Format("{0:f2} {1}", value, unit);
		}
		else if (value < 100)
		{
			value = Math.Floor( value * 10) / 10;
			return string.Format("{0:f1} {1}", value, unit);
		}
		else
		{
			value = Math.Floor( value * 1) / 1;
			return string.Format("{0:f0} {1}", value, unit);
		}
	}
}