Is there any easy way to create a class that uses IFormatProvider that writes out a user-friendly file-size?
public static string GetFileSizeString(string filePath)
{
FileInfo info = new FileInfo(@"c:\windows\notepad.exe");
long size = info.Length;
string sizeString = size.ToString(FileSizeFormatProvider); // This is where the class does its magic...
}
It should result in strings formatted something like "2,5 MB", "3,9 GB", "670 bytes" and so on.
I use this one, I get it from the web
public class FileSizeFormatProvider : IFormatProvider, ICustomFormatter
{
public object GetFormat(Type formatType)
{
if (formatType == typeof(ICustomFormatter)) return this;
return null;
}
private const string fileSizeFormat = "fs";
private const Decimal OneKiloByte = 1024M;
private const Decimal OneMegaByte = OneKiloByte * 1024M;
private const Decimal OneGigaByte = OneMegaByte * 1024M;
public string Format(string format, object arg, IFormatProvider formatProvider)
{
if (format == null || !format.StartsWith(fileSizeFormat))
{
return defaultFormat(format, arg, formatProvider);
}
if (arg is string)
{
return defaultFormat(format, arg, formatProvider);
}
Decimal size;
try
{
size = Convert.ToDecimal(arg);
}
catch (InvalidCastException)
{
return defaultFormat(format, arg, formatProvider);
}
string suffix;
if (size > OneGigaByte)
{
size /= OneGigaByte;
suffix = "GB";
}
else if (size > OneMegaByte)
{
size /= OneMegaByte;
suffix = "MB";
}
else if (size > OneKiloByte)
{
size /= OneKiloByte;
suffix = "kB";
}
else
{
suffix = " B";
}
string precision = format.Substring(2);
if (String.IsNullOrEmpty(precision)) precision = "2";
return String.Format("{0:N" + precision + "}{1}", size, suffix);
}
private static string defaultFormat(string format, object arg, IFormatProvider formatProvider)
{
IFormattable formattableArg = arg as IFormattable;
if (formattableArg != null)
{
return formattableArg.ToString(format, formatProvider);
}
return arg.ToString();
}
}
an example of use would be:
Console.WriteLine(String.Format(new FileSizeFormatProvider(), "File size: {0:fs}", 100));
Console.WriteLine(String.Format(new FileSizeFormatProvider(), "File size: {0:fs}", 10000));
Credits for http://flimflan.com/blog/FileSizeFormatProvider.aspx
There is a problem with ToString(), it's expecting a NumberFormatInfo type that implements IFormatProvider but the NumberFormatInfo class is sealed :(
If you're using C# 3.0 you can use an extension method to get the result you want:
public static class ExtensionMethods
{
public static string ToFileSize(this long l)
{
return String.Format(new FileSizeFormatProvider(), "{0:fs}", l);
}
}
You can use it like this.
long l = 100000000;
Console.WriteLine(l.ToFileSize());
Hope this helps.
OK I'm not going to wrap it up as a Format provider but rather than reinventing the wheel there's a Win32 api call to format a size string based on supplied bytes that I've used many times in various applications.
[DllImport("Shlwapi.dll", CharSet = CharSet.Auto)]
public static extern long StrFormatByteSize( long fileSize, [MarshalAs(UnmanagedType.LPTStr)] StringBuilder buffer, int bufferSize );
So I imagine you should be able to put together a provider using that as the core conversion code.
Here's a link to the MSDN spec for StrFormatByteSize.
I have taken Eduardo's answer and combined it with a similar example from elsewhere to provide additional options for the formatting.
public class FileSizeFormatProvider : IFormatProvider, ICustomFormatter
{
public object GetFormat(Type formatType)
{
if (formatType == typeof(ICustomFormatter))
{
return this;
}
return null;
}
private const string fileSizeFormat = "FS";
private const string kiloByteFormat = "KB";
private const string megaByteFormat = "MB";
private const string gigaByteFormat = "GB";
private const string byteFormat = "B";
private const Decimal oneKiloByte = 1024M;
private const Decimal oneMegaByte = oneKiloByte * 1024M;
private const Decimal oneGigaByte = oneMegaByte * 1024M;
public string Format(string format, object arg, IFormatProvider formatProvider)
{
//
// Ensure the format provided is supported
//
if (String.IsNullOrEmpty(format) || !(format.StartsWith(fileSizeFormat, StringComparison.OrdinalIgnoreCase) ||
format.StartsWith(kiloByteFormat, StringComparison.OrdinalIgnoreCase) ||
format.StartsWith(megaByteFormat, StringComparison.OrdinalIgnoreCase) ||
format.StartsWith(gigaByteFormat, StringComparison.OrdinalIgnoreCase)))
{
return DefaultFormat(format, arg, formatProvider);
}
//
// Ensure the argument type is supported
//
if (!(arg is long || arg is decimal || arg is int))
{
return DefaultFormat(format, arg, formatProvider);
}
//
// Try and convert the argument to decimal
//
Decimal size;
try
{
size = Convert.ToDecimal(arg);
}
catch (InvalidCastException)
{
return DefaultFormat(format, arg, formatProvider);
}
//
// Determine the suffix to use and convert the argument to the requested size
//
string suffix;
switch (format.Substring(0, 2).ToUpper())
{
case kiloByteFormat:
size = size / oneKiloByte;
suffix = kiloByteFormat;
break;
case megaByteFormat:
size = size / oneMegaByte;
suffix = megaByteFormat;
break;
case gigaByteFormat:
size = size / oneGigaByte;
suffix = gigaByteFormat;
break;
case fileSizeFormat:
if (size > oneGigaByte)
{
size /= oneGigaByte;
suffix = gigaByteFormat;
}
else if (size > oneMegaByte)
{
size /= oneMegaByte;
suffix = megaByteFormat;
}
else if (size > oneKiloByte)
{
size /= oneKiloByte;
suffix = kiloByteFormat;
}
else
{
suffix = byteFormat;
}
break;
default:
suffix = byteFormat;
break;
}
//
// Determine the precision to use
//
string precision = format.Substring(2);
if (String.IsNullOrEmpty(precision))
{
precision = "2";
}
return String.Format("{0:N" + precision + "}{1}", size, suffix);
}
private static string DefaultFormat(string format, object arg, IFormatProvider formatProvider)
{
IFormattable formattableArg = arg as IFormattable;
if (formattableArg != null)
{
return formattableArg.ToString(format, formatProvider);
}
return arg.ToString();
}
}
using C# 9.0 syntax can be written like this:
public static string ToFormatSize(ulong size)
{
return size switch
{
ulong s when s < 1024 => $"{size} bytes",
ulong s when s < (1024 << 10) => $"{Math.Round(size / 1024D, 2)} KB",
ulong s when s < (1024 << 20) => $"{Math.Round(size * 1D / (1024 << 10), 2)} MB",
ulong s when s < (1024 << 30) => $"{Math.Round(size * 1D / (1024L << 20), 2)} GB",
ulong s when s < (1024 << 40) => $"{Math.Round(size * 1D / (1024L << 30), 2)} TB",
ulong s when s < (1024 << 50) => $"{Math.Round(size * 1D / (1024L << 40), 2)} PB",
ulong s when s < (1024 << 60) => $"{Math.Round(size * 1D / (1024L << 50), 2)} EB",
_ => $"{size} bytes"
};
}