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
这个问题很老了,但是一个非常快速的c#函数可以是:
public static string PrettyPrintBytes(long numBytes)
{
if (numBytes < 1024)
return $"{numBytes} B";
if (numBytes < 1048576)
return $"{numBytes / 1024d:0.##} KB";
if (numBytes < 1073741824)
return $"{numBytes / 1048576d:0.##} MB";
if (numBytes < 1099511627776)
return $"{numBytes / 1073741824d:0.##} GB";
if (numBytes < 1125899906842624)
return $"{numBytes / 1099511627776d:0.##} TB";
if (numBytes < 1152921504606846976)
return $"{numBytes / 1125899906842624d:0.##} PB";
return $"{numBytes / 1152921504606846976d:0.##} EB";
}
每次调用只有一次强制转换和一次除法,最多只能进行6次比较。在进行基准测试时,我发现字符串插值比使用string . format()快得多。
其他回答
我喜欢使用以下方法(它支持高达tb,这在大多数情况下已经足够了,但它可以很容易地扩展):
private string GetSizeString(long length)
{
long B = 0, KB = 1024, MB = KB * 1024, GB = MB * 1024, TB = GB * 1024;
double size = length;
string suffix = nameof(B);
if (length >= TB) {
size = Math.Round((double)length / TB, 2);
suffix = nameof(TB);
}
else if (length >= GB) {
size = Math.Round((double)length / GB, 2);
suffix = nameof(GB);
}
else if (length >= MB) {
size = Math.Round((double)length / MB, 2);
suffix = nameof(MB);
}
else if (length >= KB) {
size = Math.Round((double)length / KB, 2);
suffix = nameof(KB);
}
return $"{size} {suffix}";
}
请记住,这是为c# 6.0(2015)编写的,因此对于较早的版本可能需要进行一些编辑。
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/
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);
}
}
另一种皮肤的方法,没有任何类型的循环和负大小支持(对文件大小增量有意义):
public static class Format
{
static string[] sizeSuffixes = {
"B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
public static string ByteSize(long size)
{
Debug.Assert(sizeSuffixes.Length > 0);
const string formatTemplate = "{0}{1:0.#} {2}";
if (size == 0)
{
return string.Format(formatTemplate, null, 0, sizeSuffixes[0]);
}
var absSize = Math.Abs((double)size);
var fpPower = Math.Log(absSize, 1000);
var intPower = (int)fpPower;
var iUnit = intPower >= sizeSuffixes.Length
? sizeSuffixes.Length - 1
: intPower;
var normSize = absSize / Math.Pow(1000, iUnit);
return string.Format(
formatTemplate,
size < 0 ? "-" : null, normSize, sizeSuffixes[iUnit]);
}
}
下面是测试套件:
[TestFixture] public class ByteSize
{
[TestCase(0, Result="0 B")]
[TestCase(1, Result = "1 B")]
[TestCase(1000, Result = "1 KB")]
[TestCase(1500000, Result = "1.5 MB")]
[TestCase(-1000, Result = "-1 KB")]
[TestCase(int.MaxValue, Result = "2.1 GB")]
[TestCase(int.MinValue, Result = "-2.1 GB")]
[TestCase(long.MaxValue, Result = "9.2 EB")]
[TestCase(long.MinValue, Result = "-9.2 EB")]
public string Format_byte_size(long size)
{
return Format.ByteSize(size);
}
}
下面是一个Log10的方法:
using System;
class Program {
static string NumberFormat(double n) {
var n2 = (int)Math.Log10(n) / 3;
var n3 = n / Math.Pow(1e3, n2);
return String.Format("{0:f3}", n3) + new[]{"", " k", " M", " G"}[n2];
}
static void Main() {
var s = NumberFormat(9012345678);
Console.WriteLine(s == "9.012 G");
}
}
https://learn.microsoft.com/dotnet/api/system.math.log10