我使用下面的Long扩展方法将其转换为人类可读的大小字符串。这个方法是在Stack Overflow上发布的相同问题的Java解决方案的c#实现。

/// <summary>
/// Convert a byte count into a human readable size string.
/// </summary>
/// <param name="bytes">The byte count.</param>
/// <param name="si">Whether or not to use SI units.</param>
/// <returns>A human readable size string.</returns>
public static string ToHumanReadableByteCount(
    this long bytes
    , bool si
)
{
    var unit = si
        ? 1000
        : 1024;

    if (bytes < unit)
    {
        return $"{bytes} B";
    }

    var exp = (int) (Math.Log(bytes) / Math.Log(unit));

    return $"{bytes / Math.Pow(unit, exp):F2} " +
           $"{(si ? "kMGTPE" : "KMGTPE")[exp - 1] + (si ? string.Empty : "i")}B";
}

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。

这里没有什么东西完全符合我的需要，我根据这个线程制作了我自己的，所以这里是我的长扩展，允许您根据标准选择格式要求。

绝对不是最快的，但很灵活。支持EB/EiB。

// <summary>
/// <paramref name="byteCount"/> The original size in bytes ( 8 bits )
/// <paramref name="notationFormat"/> is supported in the following ways:
/// [    'B' / 'b' : Binary :   Kilobyte (KB) is 1024 bytes, Megabyte (MB) is 1048576 bytes, etc    ]
/// [    'I' / 'i' : IEC:       Kibibyte (KiB) is 1024 bytes, Mebibyte (MiB) is 1048576 bytes, etc    ]
/// [    'D' / 'd' : Decimal :  Kilobyte (KB) is 1000 bytes, Megabyte (MB) is 1000000 bytes, etc    ]
/// </summary>

public static string ToDataSizeString( this long byteCount, char notationFormat = 'b' )
{
    char[] supportedFormatChars = { 'b', 'i', 'd' };

    var lowerCaseNotationFormat = char.ToLowerInvariant( notationFormat );

    // Stop shooting holes in my ship!
    if ( !supportedFormatChars.Contains( lowerCaseNotationFormat ) )
    {
        throw new ArgumentException( $"notationFormat argument '{notationFormat}' not supported" );
    }

    long ebLimit = 1152921504606846976;
    long pbLimit = 1125899906842624;
    long tbLimit = 1099511627776;
    long gbLimit = 1073741824;
    long mbLimit = 1048576;
    long kbLimit = 1024;

    var ebSuffix = "EB";
    var pbSuffix = "PB";
    var tbSuffix = "TB";
    var gbSuffix = "GB";
    var mbSuffix = "MB";
    var kbSuffix = "KB";
    var bSuffix  = " B";

    switch ( lowerCaseNotationFormat )
    {
        case 'b':
            // Sweet as
            break;

        case 'i':
            // Limits stay the same, suffixes need changed
            ebSuffix = "EiB";
            pbSuffix = "PiB";
            tbSuffix = "TiB";
            gbSuffix = "GiB";
            mbSuffix = "MiB";
            kbSuffix = "KiB";
            bSuffix  = "  B";
            break;

        case 'd':
            // Suffixes stay the same, limits need changed
            ebLimit = 1000000000000000000;
            pbLimit = 1000000000000000;
            tbLimit = 1000000000000;
            gbLimit = 1000000000;
            mbLimit = 1000000;
            kbLimit = 1000;
            break;

        default:
            // Should have already Excepted, but hey whatever
            throw new ArgumentException( $"notationFormat argument '{notationFormat}' not supported" );

    }

    string fileSizeText;

    // Exa/Exbi sized
    if ( byteCount >= ebLimit )
    {
        fileSizeText = $"{( (double)byteCount / ebLimit ):N1} {ebSuffix}";
    }
    // Peta/Pebi sized
    else if ( byteCount >= pbLimit )
    {
        fileSizeText = $"{( (double)byteCount / pbLimit ):N1} {pbSuffix}";
    }
    // Tera/Tebi sized
    else if ( byteCount >= tbLimit )
    {
        fileSizeText = $"{( (double)byteCount / tbLimit ):N1} {tbSuffix}";
    }
    // Giga/Gibi sized
    else if ( byteCount >= gbLimit )
    {
        fileSizeText = $"{( (double)byteCount / gbLimit ):N1} {gbSuffix}";
    }
    // Mega/Mibi sized
    else if ( byteCount >= mbLimit )
    {
        fileSizeText = $"{( (double)byteCount / mbLimit ):N1} {mbSuffix}";
    }
    // Kilo/Kibi sized
    else if ( byteCount >= kbLimit )
    {
        fileSizeText = $"{( (double)byteCount / kbLimit ):N1} {kbSuffix}";
    }
    // Byte sized
    else
    {
        fileSizeText = $"{byteCount} {bSuffix}";
    }

    return fileSizeText;
}

int size = new FileInfo( filePath ).Length / 1024;
string humanKBSize = string.Format( "{0} KB", size );
string humanMBSize = string.Format( "{0} MB", size / 1024 );
string humanGBSize = string.Format( "{0} GB", size / 1024 / 1024 );

我猜你要找的是“1.4 MB”而不是“1468006字节”?

我不认为在。net中有内置的方法来做到这一点。你只需要找出哪个单元是合适的，然后格式化它。

编辑:这里有一些示例代码来做到这一点:

http://www.codeproject.com/KB/cpp/formatsize.aspx

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));
}