C#如何截取我要的数据

有一个数据，如何截取我想要的长度 在我判断头帧后 我只想要后面的7位

img

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO.Ports;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using static System.Windows.Forms.VisualStyles.VisualStyleElement;

namespace Ck
{

    public partial class Form1 : Form
    {
        string timeStr = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
        
        private List<byte> buffer = new List<byte>(1024);
        byte[] receiveBuffer = new byte[10];
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load_1(object sender, EventArgs e)
        {
            comboBox1.Items.AddRange(System.IO.Ports.SerialPort.GetPortNames());
            serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived);
        }
        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                if (serialPort1.IsOpen)
                {
                    serialPort1.Close();
                    button1.Text = "点击打开串口";
                }
                else
                {
                    serialPort1.PortName = comboBox1.Text;
                    serialPort1.Open();
                    button1.Text = "点击关闭串口";
                }
            }
            catch (Exception ex)
            {
                //捕获可能发生的异常并进行处理

                //捕获到异常，创建一个新的对象，之前的不可以再用
                serialPort1 = new System.IO.Ports.SerialPort();
                //刷新COM口选项
                comboBox1.Items.Clear();
                comboBox1.Items.AddRange(System.IO.Ports.SerialPort.GetPortNames());
                //响铃并显示异常给用户
                System.Media.SystemSounds.Beep.Play();
                button1.Text = "打开串口";
                button1.BackColor = Color.ForestGreen;
                MessageBox.Show(ex.Message);
            }

        }

        private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            string abc;
            // 检查是否允许跨线程调用控件，这里为了简化代码直接禁用了该功能
            CheckForIllegalCrossThreadCalls = false;


            // 读取所有可用字节数
            int bytesToRead = serialPort1.BytesToRead;

            //用于存储接收到的数据
            byte[] receiveBuffer = new byte[bytesToRead];

            //从串口读取数据
            serialPort1.Read(receiveBuffer, 0, bytesToRead);
            buffer.AddRange(receiveBuffer);
            //将接收到的数据转换为字符串格式
            string receivedString = BitConverter.ToString(receiveBuffer).Replace("-", "");
            //将字符串追加至文本框中
            if (buffer[0] ==0x68)
            {

                StreamWriter sw = new StreamWriter(@"C:\Users\guoxiaoru\Desktop\ACVB.txt", true);
                sw.WriteLine(receivedString, "\n");
                sw.Close(); 
                
            }

        }  
    }
}

你不是已经有 byte 数组了吗？直接 byte[byte.Length - 7] 循环到 byte.Length 组一个新数组就可以了

或者，你写入的时候， write(byte,byte.Length -7,7)