Reading From a Text File in C#

Question

I have the following program that will send (output) information to a text file, but now I want to read (input) from the text file. Any suggestions would be greatly appreci

Answer 1

Try this:

if(result == DialogResult.OK && fileName != null)
{
    try
    {
        var fileText=File.ReadAllText(fileName);
    }
    catch(Exception ex)
    {
        //Handle exception here
    }
}

It will read all the data from the selected file into the fileText variable.

Answer 2

Sample program demonstrating FILE i/o in C#

class Items
{
  public int itemID { get; set; }
  public string itemName { get; set; }
  public int itemNo { get; set; }
  public string pkgdate { get; set; }
}

class Program
{
  private static string connectionString = "...";

  static void Main(string[] args)
  {
    string streadpath = @"I:\itemdata.txt";
    string stwritepath = @"I:\itemdata1.txt";
    string stcopypath = @"I:\itemdata2.txt";

    List<Items> li_all = new List<Items>();
    List<Items> li_db = new List<Items>();
    List<Items> li_valid = new List<Items>();
    List<Items> li_invalid = new List<Items>();

    li_all = stread_file(streadpath);
    li_invalid = validate(li_all);
    li_db = retrievefromDB();
    bool x = stwrite_invalid(li_db, stwritepath);
    bool y = stcopy_file(streadpath, stcopypath);
  }

  static List<Items> stread_file(string stpath)
  {
    List<Items> stli = new List<Items>();
    using (StreamReader SR = new StreamReader(stpath))
    {
      string line = "";
      while ((line = SR.ReadLine()) != null)
      {
        string[] linevalues = line.Split(',');
        Items obj = new Items();
        obj.itemID = int.Parse(linevalues[0]);
        obj.itemName = linevalues[1];
        obj.itemNo = int.Parse(linevalues[2]);
        obj.pkgdate = linevalues[3];
        stli.Add(obj);
      }
    }
    return stli;
  }

  static List<Items> validate(List<Items> stli)
  {
    List<Items> li_valid = new List<Items>();
    List<Items> li_invalid = new List<Items>();
    DateTime parsed;
    foreach (Items stit in stli)
    {
      if(DateTime.TryParseExact(stit.pkgdate, "MM/dd/yyyy",
      CultureInfo.InvariantCulture,
      DateTimeStyles.None, out parsed))
      {
        li_valid.Add(stit);
      }
      else
      {
        li_invalid.Add(stit);
      }
    }
    InsertDataToDb(li_valid);
    return li_invalid;
  }

  static bool stwrite_invalid(List<Items> stli,string stpath)
  {
    using (StreamWriter SW = new StreamWriter(stpath))
    {
      foreach(Items stit in stli)
      {
        SW.WriteLine(stit.itemID + "," + stit.itemName + "," + stit.itemNo + "," + stit.pkgdate);
      }
    }
    return true;
  }

  static bool stcopy_file(string stsourcepath, string stdestinationpath)
  {
    File.Copy(stsourcepath, stdestinationpath);
    return true;
  }

  static void InsertDataToDb(List<Items> stli)
  {
    var records = stli;
    using (SqlConnection con = new SqlConnection(connectionString))
    {
      StringBuilder nonQuery = new StringBuilder();
      foreach (var item in records)
      {
        nonQuery.AppendFormat("INSERT INTO dbo.Smartphone VALUES ({0}, '{1}', {2}, '{3}');",
        item.itemID,
        item.itemName,
        item.itemNo,
        item.pkgdate);
      }
      SqlCommand cmd = new SqlCommand(nonQuery.ToString(),con);
      con.Open();
      cmd.ExecuteNonQuery();
      con.Close();
    }
  }

  static List<Items> retrievefromDB()
  {
    List<Items> stli = new List<Items>();
    DataTable dt = new DataTable();
    SqlConnection con = new SqlConnection(connectionString);
    con.Open();
    SqlCommand cmd = new SqlCommand("select * from dbo.Smartphone", con);
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    da.Fill(dt);
    con.Close();
    if (dt.Rows.Count > 0)
    {
      for (int i = 0; i < dt.Rows.Count; i++)
      {
        Items obj = new Items();
        obj.itemID = (int)dt.Rows[i]["ID"];
        obj.itemName = dt.Rows[i]["Name"].ToString();
        obj.itemNo = (int)dt.Rows[i]["Num"];
        obj.pkgdate = dt.Rows[i]["RDate"].ToString();
        stli.Add(obj);
      }
    }
    return stli;
  }
}