Add Row, Return Int Pointer

David Smith

What would be the logic to add row , return row int pointer below:

public static int AddRowReturnIntPointer(ref DataTable datatable)
{
try
{
return 0;
}
catch (Exception ex)
{
throw new Exception("AddRowReturnIntPointer: \n" + ex.Message);
}
}

9 Replies

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Vulpes11y ago
I didn't know it was an extension method (no 'this') or that it was supposed to add a row. I just thought that it was returning the index of the last added row.

Anyway, if it's adding a new row and then returning the index, that's a straightforward matter:

using System;
using System.Data;

static class TableExtensions
{
public static int AddRowReturnIndex(this DataTable datatable, params object[] values)
{
try
{
DataRow datarow = datatable.Rows.Add(values);
return datatable.Rows.IndexOf(datarow);
}
catch (Exception ex)
{
throw new Exception("AddRowReturnIntPointer: \n" + ex.Message);
}
}
}

class Program
{
static void Main()
{
var dt = new DataTable();
int index;
dt.Columns.Add("value", typeof(decimal));
index = dt.AddRowReturnIndex(5m);
Console.WriteLine(index);
index = dt.AddRowReturnIndex(2m);
Console.WriteLine(index);
Console.WriteLine();
foreach(DataRow dr in dt.Rows) Console.WriteLine(dr["Value"]);
Console.ReadKey();
}
}

As expected, the output is:

0
1

5
2
David Smith11y ago
Vuples so are saying we dont add the row in the extension method itself. If that's the case the method name needs to be something else. lol. I thought add a row, then return the pointer.
Vulpes11y ago
We added two rows in these lines:

dt.Rows.Add(5m);
dt.Rows.Add(2m);
David Smith11y ago
Vuples, I dont see where we added a row, I just see where we are checking for count.
Vulpes11y ago
Sure, try this little program:

using System;
using System.Data;

class Program
{
public static int AddRowReturnIndex(DataTable datatable)
{
try
{
if(datatable.Rows.Count > 0)
{
return datatable.Rows.Count - 1;
}
else
{
return -1; // say, if no records in table
}
}
catch (Exception ex)
{
throw new Exception("AddRowReturnIntPointer: \n" + ex.Message);
}
}

static void Main()
{
var dt = new DataTable();
dt.Columns.Add("value", typeof(decimal));
dt.Rows.Add(5m);
dt.Rows.Add(2m);

DataView dv = dt.DefaultView;
dv.Sort = "Value";
foreach(DataRowView drv in dv) Console.WriteLine(drv["Value"]);
Console.WriteLine();
foreach(DataRow dr in dt.Rows) Console.WriteLine(dr["Value"]);
Console.WriteLine();
Console.WriteLine(AddRowReturnIndex(dt));
Console.ReadKey();
}
}

The output is :

2
5

5
2

1

So although the DataView has been sorted, the DataTable hasn't and the last record added (namely with Value = 2m) has an index of 1.

BTW, no need to use a reference parameter for the DataTable as you're not assigning a new object to it.
David Smith11y ago
Vuples could you give me an example in the function below. I learn by visual.

public static int AddRowReturnIntPointer(ref DataTable datatable)
{
try
{
return 0;
}
catch (Exception ex)
{
throw new Exception("AddRowReturnIntPointer: \n" + ex.Message);
}
}
Vulpes11y ago
Sorting and filtering will only affect the DataView associated with the DataTable, not the DataTable itself.

So, unless you've called ToTable() on the DataView and assigned it back to the same variable, datatable.Rows.Count - 1 should get the index of the last row added to the DataTable as Wim said initially.
David Smith11y ago
That's exactly what I am trying to do. There will be filtering or sorting done. The int pointer is pointing to the new row index that was just added. How would the logic be set up?
Wim Sturkenboom11y ago
Maybe you can explain with a little more detail. What is the intpointer supposed to be. the index of the new row in the datatable?

As rows are added (to my knowledge) at the end, it could be a simple matter of returning datatable.Rows.Count -1 .

This assumes that there is no filtering / sorting done.