c#中long到十进制的转换

Question

我有一个值存储在“long”类型的变量中。

long fileSizeInBytes = FileUploadControl.FileContent.Length;
Decimal fileSizeInMB = Convert.ToDecimal(fileSizeInBytes / (1024 * 1024));

我想将 fileSizeInBytes 转换为四舍五入到小数点后 2 位的十进制数（例如：1.74、2.45、3.51）但我无法获得所需的结果。结果我只得到一位没有小数位的数字。有人可以帮我吗？？

感谢期待

Answer 1

Decimal fileSizeInMB = Convert.ToDecimal(fileSize) / (1024.0m * 1024.0m);

您正在做的是将文件大小除以一个整数，结果是 整数，而不是小数。剩下的会被砍掉。

Answer 2

我没有看到 fileSize 在任何地方声明 - 但我会假设它很长。所以fileSize / (1024 * 1024) 被强制为一个不包含任何小数位的长值，所以你会得到类似的东西：

Convert.ToDecimal(someLongValue)

不会有任何小数位。先将除法转换为双精度（或其他小数），然后再将其传递给Convert.ToDecimal

Answer 3

这是我用来显示文件大小的函数

//---------------------------------------------------------------------------------------------------------------------------------
        /// <summary>
        /// Formats from bytes to KB,MB,GB,TB 
        /// </summary>
        /// <param name="number">Bytes to format</param>
        /// <returns></returns>
        public static string AutoFileSize(long number)
        {
            double tmp = number;
            string suffix = " B ";
            if (tmp > 1024) { tmp = tmp / 1024; suffix = " KB"; }
            if (tmp > 1024) { tmp = tmp / 1024; suffix = " MB"; }
            if (tmp > 1024) { tmp = tmp / 1024; suffix = " GB"; }
            if (tmp > 1024) { tmp = tmp / 1024; suffix = " TB"; }
            return tmp.ToString("n") + suffix;
        }

Answer 4

可能有点晚了，但在这里您或多或少拥有文件大小瓦等所需的一切

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Globalization;
using System.Runtime.InteropServices;
using System.Threading;

namespace ConsoleApplication1
{ 

    class Program
    {

        /// <summary>
        /// Formats the given size to the order of magniture given
        /// Order is 1 for KB, 2 for MB etc up to 8, after that you get exponents for the same notations
        /// </summary>
        /// <param name="size">The total size in bytes</param>
        /// <param name="order">+1 for each 1024 B,M,... 0 for nothing</param>
        /// <param name="unit">Usually you will want B for bytes denotation, but maybe "bit" or "bi" or W for watt</param>
        /// <param name="decimal_places">Number of desired decimal places</param>
        /// <param name="add_space">Separate KB MB etc from the number with a space?</param>
        /// <returns>Formatted size</returns>
        public static string FormatSize(string unit, double size, int order, int decimal_places, bool add_space) {

            string[] suffixes = new string[] {"", "K","M","G","T","P","E","Z","Y"};

            int exponent = order - 8 > 0 ? order - 8 : 0;
            order -= exponent;

            string suffix = suffixes[order];

            while (order > 0) {
                size /= 1024;
                order--;
            }

            string sDecimals = new String('0', decimal_places);
            string sExponent = exponent != 0 ? "E" + exponent : "";
            string dot = decimal_places > 0 ? "." : "";

            return size.ToString("#,##0" + dot + sDecimals + sExponent) + (add_space ? " " : "") + suffix + unit;
        }

        public static void Main(string[] Args)
        {
            Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;

            string sz;
            sz = FormatSize("B", 1024, 1, 0, false);
            Console.WriteLine(sz);
            sz = FormatSize("B", 1024*1024 + 512, 1, 0, true);
            Console.WriteLine(sz);
            sz = FormatSize("W", 1024 * 1024 + 512, 1, 2, true);
            Console.WriteLine(sz);
            sz = FormatSize("B", 1024 * 1024 + 512, 2, 2, true);
            Console.WriteLine(sz);
            sz = FormatSize("B", 1024 * 1024 * 1024 + 1024 * 1024 * 1024 / 2, 3, 0, false);
            Console.WriteLine(sz);
            sz = FormatSize("bit", 1024 * 1024 * 1024 + 1024 * 1024 * 1024 / 2, 3, 1, false);
            Console.WriteLine(sz);
            sz = FormatSize("B", 1024 * 1024 * 1024 + 1024 * 1024 * 1024 / 2 - 1, 3, 2, false);
            Console.WriteLine(sz);
            sz = FormatSize("Ω", 1024 * 1024 * 1024 + 1024 * 1024 * 1024 / 2 - 1, 3, 1, false);
            Console.WriteLine(sz);
            sz = FormatSize("B", 1024 * 1024 * 1024 + 1024 * 1024 * 1024 / 2 - 10000000, 3, 2, false);
            Console.WriteLine(sz);
            sz = FormatSize("B", 1024 * 1024 * 1024 + 1024 * 1024 * 1024 / 2 - 1, 3, 0, false);
            Console.WriteLine(sz);
            sz = FormatSize("bit", 1208925819614629174706176f, 9, 2, true);
            Console.WriteLine(sz);
        }
    }
}

这是一些输出：

1KB
1,025 KB
1,024.50 KW
1.00 MB
2GB
1.5Gbit
1.50GB
1.5GΩ
1.49GB
1GB
1.00E1 Ybit