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c# - 了解 If 语句字节运算符

问题描述

我已经下载了一些USB 控制继电器开关的源代码。我需要为应用程序操作此代码，但无法理解字节运算符。

我看过移位运算符，我知道它们正在将位移位到 2 的下一个幂。下面是我正在努力解决的函数：

byte[] SerBuf = new byte[64];
byte states = 0;
private void button_pressed(object sender, MouseEventArgs e)
       {
           // Check type of sender to make sure it is a button
           if (sender is Button)
           {
               if (usb_found == 1)
               {
                   Button button = (Button)sender;
                   // Check the title of the button for which realy we wish to change
                   // And then check the state of that relay and send the appropriate command to turn it on or off
                   switch (button.Text.ToString())
                   {
                       case "Relay 1":
                           if ((states & 0x01) == 0) SerBuf[0] = 0x65; //<this is the bit I don't understand
                           else SerBuf[0] = 0x6F;
                           //Thread.Sleep(2000);
                           break;
                       case "Relay 2":
                           if ((states & (0x01 << 1)) == 0) SerBuf[0] = 0x66; //<this is the bit I don't understand
                           else SerBuf[0] = 0x70;
                           break;
                       case "Both":
                           SerBuf[0] = 0x64;
                           break;
                       case "None":
                           SerBuf[0] = 0x6E;
                           break;
                   }
                   transmit(1); // this sends the new buffer to the relay board

               }
           }

我不明白的是正在评估什么if ((states & 0x01) == 0)

该States字节介于 0 和 3 之间，具体取决于两个继电器开关中的哪一个处于活动状态。

在0x01做什么？

标签： c#byte

解决方案

&运算符是位与运算符。它逐位比较两个操作数。只有当一个位置的两个位都被设置时，结果中的相应位才会被设置。

因此，假设您有a和作为位字符串呈现的位置b是和作为。然后写成位串是因为a00001101b00001011a & b00001001

           +----- no bit is set
           |+---- both bits are set
           ||+--- only one bit is set  
           |||+-- only one bit is set  
           ||||+- both bits are set
           vvvvv
a     = 00001101
b     = 00001011
----------------
a & b = 00001001

所以换句话说(states & 0x01) == 0，当且仅当states是偶数时为真，即写为以 . 结尾的位字符串0。请记住，它0x01被00000001写为位字符串。

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