Create second column in Datatable

Question

I have a DataTable where with the code:

DT.Column.Add("1ª", gettype(int32))  
    For I = 1 To 30  
        DT.Rows.Add(I)  
    Next(I)

This For lists column 1 from 1 to 30. 'DT is declared with a new DataTable, in this case the Prog does everything right, but I would like to know if it is possible for me to add a second column without being through:

DT.Column.Add("1ª", gettype(int32))  
    For I = 1 To 30    
        DT.Rows.Add(I, I*2)    
    Next(I) 

This would be necessary as the formula in the second column varies according to the value of I on each line. Examples and/or help in C# are welcome.
Working with lines I dominate relatively well, but spine is always a headache for me.

I tried something like:

For I = 1 To 30  
    DT.Rows.Add(I)  
Next(I)  
DT.Column.Add("2ª", gettype(int32))
For I = 1 to 30
  DT.Rows.Add(I)
Next(I)

But without any success, it just creates column 2 and adds data to column 1.

Answer 1

If I understand what you want, probably the solution is to do it this way:

DataTable DT = new DataTable();
DT.Columns.Add("1ª", typeof(int));
DT.Columns.Add("2ª", typeof(int));
for (int i = 0; i < 30; i++)
{
    var row = DT.NewRow();
    row["1ª"] = i;
    row["2ª"] = i;
    DT.Rows.Add(row);
}

Or that:

DataTable DT = new DataTable();
DT.Columns.Add("1ª", typeof(int));
DT.Columns.Add("2ª", typeof(int));
for (int i = 0; i < 30; i++)
{
    DT.Rows.Add(i, i);
}