我如何获得一个人类可读的文件大小字节缩写使用。net ?
例子: 输入7,326,629,显示6.98 MB
我如何获得一个人类可读的文件大小字节缩写使用。net ?
例子: 输入7,326,629,显示6.98 MB
当前回答
为了获得人类可读的字符串,就像用户在Windows环境中习惯的那样,你应该使用StrFormatByteSize():
using System.Runtime.InteropServices;
...
private long mFileSize;
[DllImport("Shlwapi.dll", CharSet = CharSet.Auto)]
public static extern int StrFormatByteSize(
long fileSize,
[MarshalAs(UnmanagedType.LPTStr)] StringBuilder buffer,
int bufferSize);
public string HumanReadableFileSize
{
get
{
var sb = new StringBuilder(20);
StrFormatByteSize(mFileSize, sb, 20);
return sb.ToString();
}
}
我在这里找到了这个: http://csharphelper.com/blog/2014/07/format-file-sizes-in-kb-mb-gb-and-so-forth-in-c/
其他回答
又多了一种方法,不管怎样。我喜欢上面提到的@humbads优化解决方案,所以复制了原理,但我实现了一点不同。
我认为它是否应该是一个扩展方法是有争议的(因为不是所有的long都必须是字节大小),但我喜欢它们,当我下次需要它时,我可以在某个地方找到它!
关于单位,我想我从来没有说过“Kibibyte”或“Mebibyte”,虽然我对这种强制而非进化的标准持怀疑态度,但我认为从长远来看,这将避免混淆。
public static class LongExtensions
{
private static readonly long[] numberOfBytesInUnit;
private static readonly Func<long, string>[] bytesToUnitConverters;
static LongExtensions()
{
numberOfBytesInUnit = new long[6]
{
1L << 10, // Bytes in a Kibibyte
1L << 20, // Bytes in a Mebibyte
1L << 30, // Bytes in a Gibibyte
1L << 40, // Bytes in a Tebibyte
1L << 50, // Bytes in a Pebibyte
1L << 60 // Bytes in a Exbibyte
};
// Shift the long (integer) down to 1024 times its number of units, convert to a double (real number),
// then divide to get the final number of units (units will be in the range 1 to 1023.999)
Func<long, int, string> FormatAsProportionOfUnit = (bytes, shift) => (((double)(bytes >> shift)) / 1024).ToString("0.###");
bytesToUnitConverters = new Func<long,string>[7]
{
bytes => bytes.ToString() + " B",
bytes => FormatAsProportionOfUnit(bytes, 0) + " KiB",
bytes => FormatAsProportionOfUnit(bytes, 10) + " MiB",
bytes => FormatAsProportionOfUnit(bytes, 20) + " GiB",
bytes => FormatAsProportionOfUnit(bytes, 30) + " TiB",
bytes => FormatAsProportionOfUnit(bytes, 40) + " PiB",
bytes => FormatAsProportionOfUnit(bytes, 50) + " EiB",
};
}
public static string ToReadableByteSizeString(this long bytes)
{
if (bytes < 0)
return "-" + Math.Abs(bytes).ToReadableByteSizeString();
int counter = 0;
while (counter < numberOfBytesInUnit.Length)
{
if (bytes < numberOfBytesInUnit[counter])
return bytesToUnitConverters[counter](bytes);
counter++;
}
return bytesToUnitConverters[counter](bytes);
}
}
请求函数的测试和显著优化版本发布在这里:
c#人类可读文件大小-优化的函数
源代码:
// Returns the human-readable file size for an arbitrary, 64-bit file size
// The default format is "0.### XB", e.g. "4.2 KB" or "1.434 GB"
public string GetBytesReadable(long i)
{
// Get absolute value
long absolute_i = (i < 0 ? -i : i);
// Determine the suffix and readable value
string suffix;
double readable;
if (absolute_i >= 0x1000000000000000) // Exabyte
{
suffix = "EB";
readable = (i >> 50);
}
else if (absolute_i >= 0x4000000000000) // Petabyte
{
suffix = "PB";
readable = (i >> 40);
}
else if (absolute_i >= 0x10000000000) // Terabyte
{
suffix = "TB";
readable = (i >> 30);
}
else if (absolute_i >= 0x40000000) // Gigabyte
{
suffix = "GB";
readable = (i >> 20);
}
else if (absolute_i >= 0x100000) // Megabyte
{
suffix = "MB";
readable = (i >> 10);
}
else if (absolute_i >= 0x400) // Kilobyte
{
suffix = "KB";
readable = i;
}
else
{
return i.ToString("0 B"); // Byte
}
// Divide by 1024 to get fractional value
readable = (readable / 1024);
// Return formatted number with suffix
return readable.ToString("0.### ") + suffix;
}
1-liner(加上前缀常量)
const String prefixes = " KMGTPEY";
/// <summary> Returns the human-readable file size for an arbitrary, 64-bit file size. </summary>
public static String HumanSize(UInt64 bytes)
=> Enumerable
.Range(0, prefixes.Length)
.Where(i => bytes < 1024U<<(i*10))
.Select(i => $"{(bytes>>(10*i-10))/1024:0.###} {prefixes[i]}B")
.First();
或者,如果你想减少LINQ对象的分配,使用相同的for循环变量:
/// <summary>
/// Returns the human-readable file size for an arbitrary, 64-bit file size.
/// </summary>
public static String HumanSize(UInt64 bytes)
{
const String prefixes = " KMGTPEY";
for (var i = 0; i < prefixes.Length; i++)
if (bytes < 1024U<<(i*10))
return $"{(bytes>>(10*i-10))/1024:0.###} {prefixes[i]}B";
throw new ArgumentOutOfRangeException(nameof(bytes));
}
有一个开源项目可以做到这一点,甚至更多。
7.Bits().ToString(); // 7 b
8.Bits().ToString(); // 1 B
(.5).Kilobytes().Humanize(); // 512 B
(1000).Kilobytes().ToString(); // 1000 KB
(1024).Kilobytes().Humanize(); // 1 MB
(.5).Gigabytes().Humanize(); // 512 MB
(1024).Gigabytes().ToString(); // 1 TB
http://humanizr.net/#bytesize
https://github.com/MehdiK/Humanizer
string[] suffixes = { "B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
int s = 0;
long size = fileInfo.Length;
while (size >= 1024)
{
s++;
size /= 1024;
}
string humanReadable = String.Format("{0} {1}", size, suffixes[s]);