如何为字符串类型编写switch语句

本文关键字：switch 语句 类型 字符串 | 更新日期: 2023-09-27 18:05:43

我使用串行端口连接设备，该设备返回给我":gs# "字符串。经过长时间的检查，我几乎可以肯定问题出在切换条件，即，我的程序从不进入大小写，总是进入默认。我在一个文本框中打印了接收到的字符串，它是":GS #"!我很困惑。我错在哪里?

下面是我的代码: 
char[] lxCMD = new char[8];
.
.
.
private void serialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
  serialPort.Read(lxCMD, 0, lxCMD.Length);
  this.Invoke(new EventHandler(UpdateVar));
        }
private void UpdateVar(object sender, EventArgs e)
{
  string strRecieved = "Ack";
  if (lxCMD[0] != 0x6)
  {
    strRecieved = new string(lxCMD);
  }
  textBox1.AppendText(strRecieved);  // This line prints :GS# correctly!
  textBox1.AppendText(Environment.NewLine);
  switch(strRecieved)
    {
      case ":GS#":
          serialPort.Write("20:08:18#");
          textBox1.AppendText("1:");  
          textBox1.AppendText(Environment.NewLine);
              break;
       case "Ack":
          serialPort.Write("1");
          textBox1.AppendText("2:");
          textBox1.AppendText(Environment.NewLine);
              break;
       default:
          textBox1.AppendText("Nothing");
              break;
            }
        }

如何为字符串类型编写switch语句

正如在评论中指出的那样，您保存读取字节的char数组长度为8个字符。当你将数组转换为字符串时它会创建一个长度为8的字符串，你可以通过调用strRecieved.Length来检查例如:

textBox1.AppendText(strRecieved);  // This line prints :GS# correctly!         
textBox1.AppendText(Environment.NewLine);
Console.Out.WriteLine(strRecieved.Length); //or any other means of output - will output 8

这意味着字符串中有一些不可打印的字符(ASCII表为空)。因此情况不匹配!

由于串行端口的Read方法返回读取的字节数，尝试使用它来获得正确的子字符串。例如(I Think this work): 

char[] lxCMD = new char[8];
var bytesRead = 0; 
.
.
.
private void serialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
  bytesRead = serialPort.Read(lxCMD, 0, lxCMD.Length);
  this.Invoke(new EventHandler(UpdateVar));
        }
private void UpdateVar(object sender, EventArgs e)
{
  string strRecieved = "Ack";
  if (lxCMD[0] != 0x6)
  {
    strRecieved = new string(lxCMD);
    strRecieved = strRecieved.SubString(0, bytesRead)
  }
  textBox1.AppendText(strRecieved);  // This line prints :GS# correctly!
  textBox1.AppendText(Environment.NewLine);
  switch(strRecieved)
    {
      case ":GS#":
          serialPort.Write("20:08:18#");
          textBox1.AppendText("1:");  
          textBox1.AppendText(Environment.NewLine);
              break;
       case "Ack":
          serialPort.Write("1");
          textBox1.AppendText("2:");
          textBox1.AppendText(Environment.NewLine);
              break;
       default:
          textBox1.AppendText("Nothing");
              break;
            }
        }

将if语句中的string strreceived初始化为:

strRecieved = new string(chars.TakeWhile(c => c != ''0').ToArray());

问题是，如果输入长度不是8，则字符数组在末尾保存多个'0字符。

下面的测试演示了它:

[Test]
    public void stringConstructor_CharArrayWithSomeEmptyValues_StringWithoutEmptyValues()
    {
        var expected = "test";
        var chars = new char[expected.Length+42];
        chars[0] = expected[0];
        chars[1] = expected[1];
        chars[2] = expected[2];
        chars[3] = expected[3];
        var str = new string(chars.TakeWhile(c => c != ''0').ToArray());
        Assert.AreEqual(expected, str);
        str = new string(chars,0,chars.Length);
        Assert.AreNotEqual(expected, str);
    }
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