c# 对CSV文件操作（写入、读取、修改）

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public static void SaveCSV(DataTable dt, string fullPath)//table数据写入csv
{
  System.IO.FileInfo fi = new System.IO.FileInfo(fullPath);
  if (!fi.Directory.Exists)
  {
    fi.Directory.Create();
  }
  System.IO.FileStream fs = new System.IO.FileStream(fullPath, System.IO.FileMode.Create, 
    System.IO.FileAccess.Write);
  System.IO.StreamWriter sw = new System.IO.StreamWriter(fs, System.Text.Encoding.UTF8);
  string data = "";
 
  for (int i = 0; i < dt.Columns.Count; i++)//写入列名
  {
    data += dt.Columns[i].ColumnName.ToString();
    if (i < dt.Columns.Count - 1)
    {
      data += ",";
    }
  }
  sw.WriteLine(data);
 
  for (int i = 0; i < dt.Rows.Count; i++) //写入各行数据
  {
    data = "";
    for (int j = 0; j < dt.Columns.Count; j++)
    {
      string str = dt.Rows[i][j].ToString();
      str = str.Replace(""", """");//替换英文冒号 英文冒号需要换成两个冒号
      if (str.Contains(',') || str.Contains('"')
        || str.Contains('r') || str.Contains('n')) //含逗号 冒号 换行符的需要放到引号中
      {
        str = string.Format(""{0}"", str);
      }
 
      data += str;
      if (j < dt.Columns.Count - 1)
      {
        data += ",";
      }
    }
    sw.WriteLine(data);
  }
  sw.Close();
  fs.Close();
}

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public static DataTable OpenCSV(string filePath)//从csv读取数据返回table
{
  System.Text.Encoding encoding = GetType(filePath); //Encoding.ASCII;//
  DataTable dt = new DataTable();
  System.IO.FileStream fs = new System.IO.FileStream(filePath, System.IO.FileMode.Open, 
    System.IO.FileAccess.Read);
 
  System.IO.StreamReader sr = new System.IO.StreamReader(fs, encoding);
 
  //记录每次读取的一行记录
  string strLine = "";
  //记录每行记录中的各字段内容
  string[] aryLine = null;
  string[] tableHead = null;
  //标示列数
  int columnCount = 0;
  //标示是否是读取的第一行
  bool IsFirst = true;
  //逐行读取CSV中的数据
  while ((strLine = sr.ReadLine()) != null)
  {
    if (IsFirst == true)
    {
      tableHead = strLine.Split(',');
      IsFirst = false;
      columnCount = tableHead.Length;
      //创建列
      for (int i = 0; i < columnCount; i++)
      {
        DataColumn dc = new DataColumn(tableHead[i]);
        dt.Columns.Add(dc);
      }
    }
    else
    {
      aryLine = strLine.Split(',');
      DataRow dr = dt.NewRow();
      for (int j = 0; j < columnCount; j++)
      {
        dr[j] = aryLine[j];
      }
      dt.Rows.Add(dr);
    }
  }
  if (aryLine != null && aryLine.Length > 0)
  {
    dt.DefaultView.Sort = tableHead[0] + " " + "asc";
  }
 
  sr.Close();
  fs.Close();
  return dt;
}
/// 给定文件的路径，读取文件的二进制数据，判断文件的编码类型
/// <param name="FILE_NAME">文件路径</param>
/// <returns>文件的编码类型</returns>
 
public static System.Text.Encoding GetType(string FILE_NAME)
{
  System.IO.FileStream fs = new System.IO.FileStream(FILE_NAME, System.IO.FileMode.Open, 
    System.IO.FileAccess.Read);
  System.Text.Encoding r = GetType(fs);
  fs.Close();
  return r;
}
 
/// 通过给定的文件流，判断文件的编码类型
/// <param name="fs">文件流</param>
/// <returns>文件的编码类型</returns>
public static System.Text.Encoding GetType(System.IO.FileStream fs)
{
  byte[] Unicode = new byte[] { 0xFF, 0xFE, 0x41 };
  byte[] UnicodeBIG = new byte[] { 0xFE, 0xFF, 0x00 };
  byte[] UTF8 = new byte[] { 0xEF, 0xBB, 0xBF }; //带BOM
  System.Text.Encoding reVal = System.Text.Encoding.Default;
 
  System.IO.BinaryReader r = new System.IO.BinaryReader(fs, System.Text.Encoding.Default);
  int i;
  int.TryParse(fs.Length.ToString(), out i);
  byte[] ss = r.ReadBytes(i);
  if (IsUTF8Bytes(ss) || (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF))
  {
    reVal = System.Text.Encoding.UTF8;
  }
  else if (ss[0] == 0xFE && ss[1] == 0xFF && ss[2] == 0x00)
  {
    reVal = System.Text.Encoding.BigEndianUnicode;
  }
  else if (ss[0] == 0xFF && ss[1] == 0xFE && ss[2] == 0x41)
  {
    reVal = System.Text.Encoding.Unicode;
  }
  r.Close();
  return reVal;
}
 
/// 判断是否是不带 BOM 的 UTF8 格式
/// <param name="data"></param>
/// <returns></returns>
private static bool IsUTF8Bytes(byte[] data)
{
  int charByteCounter = 1;　 //计算当前正分析的字符应还有的字节数
  byte curByte; //当前分析的字节.
  for (int i = 0; i < data.Length; i++)
  {
    curByte = data[i];
    if (charByteCounter == 1)
    {
      if (curByte >= 0x80)
      {
        //判断当前
        while (((curByte <<= 1) & 0x80) != 0)
        {
          charByteCounter++;
        }
        //标记位首位若为非0 则至少以2个1开始 如:110XXXXX...........1111110X　
        if (charByteCounter == 1 || charByteCounter > 6)
        {
          return false;
        }
      }
    }
    else
    {
      //若是UTF-8 此时第一位必须为1
      if ((curByte & 0xC0) != 0x80)
      {
        return false;
      }
      charByteCounter--;
    }
  }
  if (charByteCounter > 1)
  {
    throw new Exception("非预期的byte格式");
  }
  return true;
}

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public static bool ChangeFileName(string OldPath, string NewPath) 
{
  bool re = false;
  try 
  {
    if (File.Exists(OldPath)) 
    {
      File.Move(OldPath, NewPath);
      re = true;
    }
  }
  catch 
  {
    re = false;
  }
  return re;
}

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public static bool SaveCSV(string fullPath,string Data)
{
  bool re = true;
  try
  {
    FileStream FileStream = new FileStream(fullPath, FileMode.Append);
    StreamWriter sw = new StreamWriter(FileStream, System.Text.Encoding.UTF8);
    sw.WriteLine(Data);
    //清空缓冲区
    sw.Flush();
    //关闭流
    sw.Close();
    FileStream.Close();
  }
  catch 
  {
    re = false;
  }
  return re;
}