LSB优先还是MSB优先？

本文介绍了LSB优先还是MSB优先？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我想用十六进制数转换一个十进制数，然后先用LSB通过串口发送。 我试过这个

I want to convert a decimal number in hexadecimal number and send through serial port with LSB first. I tried this

Int32 decValue = 1234056789; byte[] testBytes = new byte[4]; testBytes [0] = (byte)(decValue & 0x000000FF); testBytes [1] = (byte)((decValue >> 8) & 0x000000FF); testBytes [2] = (byte)((decValue >> 16) & 0x000000FF); testBytes [3] = (byte)((decValue >> 24) & 0x000000FF);

testBytes [0]是否包含LSB中的字节第一个或MSB优先???

Is testBytes[0] contains bytes in LSB first or MSB first???

推荐答案

严格来说，它取决于连接到RS-232电缆另一端的设备的要求。 Windows使用little-endian格式（最低有效字节优先）;我会说，大多数系统都是这样做的。但是，这不是一个规则; big-endian也被使用。例如，所谓的标准网络订单是big-endian。 请参阅： en.wikipedia/wiki/Endianness [ ^ ]。

-SA

Strictly speaking, it depends on the requirements of the device connected to the other end of your RS-232 cable. Windows uses "little-endian" formats (least significant byte goes first); I would say, most systems do the same. However, this is not a rule; "big-endian" is also used. For example, so-called standard "network order" is big-endian. Please see: en.wikipedia/wiki/Endianness[^].

—SA

这是测试方法来自msdn： msdn.microsoft/en-us/library/bb384066 .aspx [ ^ ] This is the way to test taken from msdn: msdn.microsoft/en-us/library/bb384066.aspx[^] byte[] bytes = { 0, 0, 0, 25 }; int i = BitConverter.ToInt32(bytes, 0); Console.WriteLine("int: {0}", i);

如果这打印25，那么你的计算机是big-endian - 你首先发送testBytes [3]。 如果它不打印25然后发送testBytes [ 0]首先。 但是有一个对endian_ness BitConverter.IsLittleEndian的测试。所以你可以写：

If this prints 25 then your computer is big-endian - you send testBytes [3] first. If it does not print 25 then send testBytes [0] first. There is however a test for endian_ness BitConverter.IsLittleEndian. So you can write:

byte[] bytes = { 0, 0, 0, 25 }; // If the system architecture is little-endian (that is, little end first), // reverse the byte array. if (BitConverter.IsLittleEndian) Array.Reverse(bytes); int i = BitConverter.ToInt32(bytes, 0); Console.WriteLine("int: {0}", i); // Output: int: 25

您还应该查看BitConverter.GetBytes（Int32）以将Int32转换为字节数组。 msdn.microsoft/en-us/library/de8fssa4(v=vs.110).aspx [ ^ ]