[DllImport ( "Shlwapi.dll", CharSet = CharSet.Auto )]
public static extern long StrFormatByteSize ( 
        long fileSize
        , [MarshalAs ( UnmanagedType.LPTStr )] StringBuilder buffer
        , int bufferSize );


/// <summary>
/// Converts a numeric value into a string that represents the number expressed as a size value in bytes, kilobytes, megabytes, or gigabytes, depending on the size.
/// </summary>
/// <param name="filelength">The numeric value to be converted.</param>
/// <returns>the converted string</returns>
public static string StrFormatByteSize (long filesize) {
     StringBuilder sb = new StringBuilder( 11 );
     StrFormatByteSize( filesize, sb, sb.Capacity );
     return sb.ToString();
}

来自:http://www.pinvoke.net/default.aspx/shlwapi/StrFormatByteSize.html

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]);

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

下面是一个自动确定单位的简明答案。

public static string ToBytesCount(this long bytes)
{
    int unit = 1024;
    string unitStr = "B";
    if (bytes < unit)
    {
        return string.Format("{0} {1}", bytes, unitStr);
    }
    int exp = (int)(Math.Log(bytes) / Math.Log(unit));
    return string.Format("{0:##.##} {1}{2}", bytes / Math.Pow(unit, exp), "KMGTPEZY"[exp - 1], unitStr);
}

“b”代表bit，“b”代表Byte，“KMGTPEZY”分别代表kilo, mega, giga, tera, peta, exa, zetta和yotta

可以将ISO/IEC80000纳入考虑范围:

public static string ToBytesCount(this long bytes, bool isISO = true)
{
    int unit = isISO ? 1024 : 1000;
    string unitStr = "B";
    if (bytes < unit)
    {
        return string.Format("{0} {1}", bytes, unitStr);
    }
    int exp = (int)(Math.Log(bytes) / Math.Log(unit));
    return string.Format("{0:##.##} {1}{2}{3}", bytes / Math.Pow(unit, exp), "KMGTPEZY"[exp - 1], isISO ? "i" : "", unitStr);
}

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。