report viewer sum textbox

Hello

I emphasize that the question is still unclear, but:

1. If data is bound from a database:
I prefer to have a Computed Column Specification in my Database Table.

2. If you have a method or event or ... for Update cells, compute sum in this block (After cells updated)

for example:

public void UpdateCells()
{
    // My Previous code right here...

    int sum = 0, myValue = 0;
    foreach (TextBox t in myCellCollection)
    {

        if (int.TryParse(t.Text, out myValue))
            sum += myValue;
    }

    SumText.Text = myValue.ToString();
}

You can also add all CellValues on passing them to TextBoxes, then you don't need TryParse(... and foreach(

I hope it will help.