System.Data tables data type fix on C#

Question

I have run into an issue with system.data tables where i want to print out each row for each column, however I cant find a way that dose this for mixed data types such as the ones comprised in my table.

here is the relevant code snippet:

table.Rows[0].Field<int>(i)

Which requires a date type after the field classifier, but it breaks my code if its int or string, I need a solution that will work with both as well as bool. And here is the whole class:

public DataTable MakeTable()
{
    using (DataTable table = new DataTable())
    {
        table.Columns.Add("ID", typeof(int));
        table.Columns.Add("First Name", typeof(string));
        table.Columns.Add("Surname", typeof(string));
        table.Columns.Add("Permanent?", typeof(bool));
        table.Columns.Add("Salary", typeof(int));
        table.Columns.Add("Bonus", typeof(int));
        table.Columns.Add("Day Rate", typeof(int));
        table.Columns.Add("Weeks Worked", typeof(int));

        table.Rows.Add(1, "Joe", "Bloggs", true, 40000, 5000, null, null);
        table.Rows.Add(2, "John", "Smith", true, 45000, 2500, null, null);
        table.Rows.Add(3, "Clare", "Jones", false, null, null, 350, 40);
        

        int x = 0;
        for (int i = 0; i < 8; i++)
        {
            Console.WriteLine(table.Columns[i].ColumnName + ":  " + table.Rows[0].Field<int>(i));
            Console.WriteLine();
            if (i == 4)
            {
                x++;
                if (x == 3)
                {
                    Console.WriteLine("BREAK");
                    break;
                }
                i = -1;
            }
            Console.WriteLine("\n");
                
        }
        return table;
    }
}

Any suggestions?

many thanks in advance been stuck on this all day with no avail.

`table.Rows[0][i]` gives you the field as an `object`. `Field` is an extension method added later precisely because you usually *do* want it typed. — Jeroen Mostert, Sep 06 '21 at 14:59
Also you are printing always the first line _table.Rows[0]_ I suppose you need to add another loop over the _table.Columns.Count_ and your loop over the rows (indexer i) will fail because you have not 8 rows (neither 4) — Steve, Sep 06 '21 at 15:05
@JeroenMostert Thank you, so i can just remove the .Field altogether? — Alexander, Sep 06 '21 at 15:10

Jiale Xue - MSFT · Accepted Answer · 2021-09-07T09:15:02.583

@Alexander

You may print the data as follows:

table.Rows[i][j] //represents the i-th row and the j-th column.
table.Rows[i]["j"] //represents the data whose column name is j in the ith rows.

A modified version:

for (int i = 0, x = 0 ;x< 3; i++) {
     if (i == 8) {
         x++;
         Console.WriteLine("\n");
         i = -1;
         continue;
      }
      Console.WriteLine(table.Columns[i].ColumnName + ":  " + table.Rows[x][i]);
}

Output result:

My demo:

foreach (DataRow dr in table.Rows) {
Console.Write("ID:{0,-3} First Name:{1,-5} Surname:{2,-8} Permanent?:{3,-6} Salary:{4,-5} Bonus:{5,-5} Day Rate:{6,-5} Weeks Worked:{7,-5}"//输出格式
, dr["ID"], dr["First Name"], dr["Surname"], dr["Permanent?"], dr["Salary"], dr["Bonus"], dr["Day Rate"], dr["Weeks Worked"]);
Console.WriteLine();
}

Output result:

System.Data tables data type fix on C#

1 Answers1