Make a specific column only accept numeric value in datagridview in Keypress event

• Add an event of EditingControlShowing
• In EditingControlShowing, check that if the current cell lies in the desired column.
• Register a new event of KeyPress in EditingControlShowing(if above condition is true).
• Remove any KeyPress event added previously in EditingControlShowing.
• In KeyPress event, check that if key is not digit then cancel the input.

Example:

private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
    e.Control.KeyPress -= new KeyPressEventHandler(Column1_KeyPress);
    if (dataGridView1.CurrentCell.ColumnIndex == 0) //Desired Column
    {
        TextBox tb = e.Control as TextBox;
        if (tb != null)
        {
            tb.KeyPress += new KeyPressEventHandler(Column1_KeyPress);
        }
    }
}

private void Column1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar))
    {
        e.Handled = true;
    }
}

You must use DataGridView.CellValidating Event like this :

    private void dataGridView1_CellValidating(object sender, 
                                           DataGridViewCellValidatingEventArgs e)
    {
        if (e.ColumnIndex == 1) // 1 should be your column index
        {
            int i;

            if (!int.TryParse(Convert.ToString(e.FormattedValue), out i))
            {
                e.Cancel = true;
                label1.Text ="please enter numeric";
            }
            else
            {
                // the input is numeric 
            }
        }
    }

 private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
    {
        e.Control.KeyPress -= new KeyPressEventHandler(Column1_KeyPress);
        if (dataGridView1.CurrentCell.ColumnIndex == 4) //Desired Column
        {
            TextBox tb = e.Control as TextBox;
            if (tb != null)
            {
                tb.KeyPress += new KeyPressEventHandler(Column1_KeyPress);
            }
        }

    }
    private void Column1_KeyPress(object sender, KeyPressEventArgs e)
    { 
          // allowed only numeric value  ex.10
        //if (!char.IsControl(e.KeyChar)
        //    && !char.IsDigit(e.KeyChar))
        //{
        //    e.Handled = true;
        //}

               // allowed numeric and one dot  ex. 10.23
        if (!char.IsControl(e.KeyChar)&& !char.IsDigit(e.KeyChar)
             && e.KeyChar != '.')
        {
            e.Handled = true;
        }

        // only allow one decimal point
        if (e.KeyChar == '.'
            && (sender as TextBox).Text.IndexOf('.') > -1)
        {
            e.Handled = true;
        }
    }