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DataGridView.SelectionChanged Event

Occurs when the current selection changes.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)
public event EventHandler SelectionChanged

This event occurs whenever cells are selected or the selection is canceled, whether programmatically or by user action. For example, this event is useful when you want display the sum of the currently selected cells.

When you change the value of the CurrentCell property, the SelectionChanged event occurs before the CurrentCellChanged event. Any SelectionChanged event handler accessing the CurrentCell property at this time will get its previous value.

For more information about handling events, see Consuming Events.

The following code example demonstrates the use of this event. In the example, the form displays the sum of values in the selected cells, and updates the sum when the selection changes.


using System;
using System.Drawing;
using System.Windows.Forms;

public class Form1 : Form
{
    private DataGridView DataGridView1 = new DataGridView();
    private FlowLayoutPanel FlowLayoutPanel1 = new FlowLayoutPanel();
    private Label Label1 = new Label();
    private Label Label2 = new Label();
    private Label Label3 = new Label();
    private Label Label4 = new Label();

    // Establish the main entry point for the application.
    [STAThreadAttribute()]
    public static void Main()
    {
        Application.Run(new Form1());
    }

    public Form1()
    {
        // Initialize the form.
        // This code can be replaced with designer generated code.
        AutoSize = true;

        // Set the FlowLayoutPanel1 properties.
        FlowLayoutPanel1.FlowDirection = FlowDirection.TopDown;
        FlowLayoutPanel1.Location = new System.Drawing.Point(354, 0);
        FlowLayoutPanel1.AutoSize = true;
        FlowLayoutPanel1.Controls.Add(Label1);
        FlowLayoutPanel1.Controls.Add(Label2);
        FlowLayoutPanel1.Controls.Add(Label3);
        FlowLayoutPanel1.Controls.Add(Label4);

        Controls.Add(FlowLayoutPanel1);
        Controls.Add(DataGridView1);

        // Set the Label properties.
        Label1.AutoSize = true;
        Label2.AutoSize = true;
        Label3.AutoSize = true;
    }

    protected override void OnLoad(EventArgs e)
    {
        PopulateDataGridView();
        UpdateLabelText();
        UpdateBalance();

        DataGridView1.CellValidating += new
            DataGridViewCellValidatingEventHandler(
            DataGridView1_CellValidating);
        DataGridView1.CellValidated += new DataGridViewCellEventHandler(
            DataGridView1_CellValidated);
        DataGridView1.CellValueChanged += new DataGridViewCellEventHandler(
            DataGridView1_CellValueChanged);
        DataGridView1.RowsRemoved += new DataGridViewRowsRemovedEventHandler(
            DataGridView1_RowsRemoved);
        DataGridView1.SelectionChanged += new EventHandler(
            DataGridView1_SelectionChanged);
        DataGridView1.UserAddedRow += new DataGridViewRowEventHandler(
            DataGridView1_UserAddedRow);
        DataGridView1.UserDeletingRow += new
            DataGridViewRowCancelEventHandler(DataGridView1_UserDeletingRow);

        base.OnLoad(e);
    }

    // Replace this with your own code to populate the DataGridView.
    private void PopulateDataGridView()
    {
        DataGridView1.Size = new Size(350, 400);
        DataGridView1.AllowUserToDeleteRows = true;

        // Add columns to the DataGridView.
        DataGridView1.ColumnCount = 4;
        DataGridView1.SelectionMode =
            DataGridViewSelectionMode.RowHeaderSelect;

        // Set the properties of the DataGridView columns.
        DataGridView1.Columns[0].Name = "Description";
        DataGridView1.Columns[1].Name = "Withdrawals";
        DataGridView1.Columns[2].Name = "Deposits";
        DataGridView1.Columns[3].Name = "Balance";
        DataGridView1.Columns["Description"].HeaderText = "Description";
        DataGridView1.Columns["Withdrawals"].HeaderText = "W(-)";
        DataGridView1.Columns["Deposits"].HeaderText = "D(+)";
        DataGridView1.Columns["Balance"].HeaderText = "Balance";
        DataGridView1.Columns["Balance"].ReadOnly = true;
        DataGridView1.Columns["Description"].SortMode =
            DataGridViewColumnSortMode.NotSortable;
        DataGridView1.Columns["Withdrawals"].SortMode =
            DataGridViewColumnSortMode.NotSortable;
        DataGridView1.Columns["Deposits"].SortMode =
            DataGridViewColumnSortMode.NotSortable;
        DataGridView1.Columns["Balance"].SortMode =
            DataGridViewColumnSortMode.NotSortable;

        // Add rows of data to the DataGridView.
        DataGridView1.Rows.Add(new string[] {
            "Starting Balance", "", "", "1000" });
        DataGridView1.Rows.Add(new string[] {
            "Paycheck Deposit", "", "850", "" });
        DataGridView1.Rows.Add(new string[] { "Rent", "-500", "", "" });
        DataGridView1.Rows.Add(new string[] { "Groceries", "-25", "", "" });
        DataGridView1.Rows.Add(new string[] { "Tax Return", "", "300", "" });


        // Allow the user to edit the starting balance cell
        DataGridView1.Rows[0].ReadOnly = true;
        DataGridView1.Rows[0].Cells["Balance"].ReadOnly = false;

        // Autosize the columns.
        DataGridView1.AutoResizeColumns();
    }

    private void DataGridView1_CellValueChanged(
        object sender, DataGridViewCellEventArgs e)
    {
        // Update the balance column whenever the value of any cell changes.
        UpdateBalance();
    }

    private void DataGridView1_RowsRemoved(
        object sender, DataGridViewRowsRemovedEventArgs e)
    {
        // Update the balance column whenever rows are deleted.
        UpdateBalance();
    }

    private void UpdateBalance()
    {
        int counter;
        int balance;
        int deposit;
        int withdrawal;

        // Iterate through the rows, skipping the Starting Balance row.
        for (counter = 1; counter < (DataGridView1.Rows.Count - 1);
            counter++)
        {
            deposit = 0;
            withdrawal = 0;
            balance = int.Parse(DataGridView1.Rows[counter - 1]
                .Cells["Balance"].Value.ToString());

            if (DataGridView1.Rows[counter].Cells["Deposits"].Value != null)
            {
                // Verify that the cell value is not an empty string.
                if (DataGridView1.Rows[counter]
                    .Cells["Deposits"].Value.ToString().Length != 0)
                {
                    deposit = int.Parse(DataGridView1.Rows[counter]
                        .Cells["Deposits"].Value.ToString());
                }
            }

            if (DataGridView1.Rows[counter].Cells["Withdrawals"].Value != null)
            {
                if (DataGridView1.Rows[counter]
                    .Cells["Withdrawals"].Value.ToString().Length != 0)
                {
                    withdrawal = int.Parse(DataGridView1.Rows[counter]
                        .Cells["Withdrawals"].Value.ToString());
                }
            }
            DataGridView1.Rows[counter].Cells["Balance"].Value =
                (balance + deposit + withdrawal).ToString();
        }
    }

    private void DataGridView1_SelectionChanged(object sender, EventArgs e)
    {
        // Update the labels to reflect changes to the selection.
        UpdateLabelText();
    }

    private void DataGridView1_UserAddedRow(
        object sender, DataGridViewRowEventArgs e)
    {
        // Update the labels to reflect changes to the number of entries.
        UpdateLabelText();
    }

    private void UpdateLabelText()
    {
        int WithdrawalTotal = 0;
        int DepositTotal = 0;
        int SelectedCellTotal = 0;
        int counter;

        // Iterate through all the rows and sum up the appropriate columns.
        for (counter = 0; counter < (DataGridView1.Rows.Count);
            counter++)
        {
            if (DataGridView1.Rows[counter].Cells["Withdrawals"].Value
                != null)
            {
                if (DataGridView1.Rows[counter].
                    Cells["Withdrawals"].Value.ToString().Length != 0)
                {
                    WithdrawalTotal += int.Parse(DataGridView1.Rows[counter].
                        Cells["Withdrawals"].Value.ToString());
                }
            }

            if (DataGridView1.Rows[counter].Cells["Deposits"].Value != null)
            {
                if (DataGridView1.Rows[counter]
                    .Cells["Deposits"].Value.ToString().Length != 0)
                {
                    DepositTotal += int.Parse(DataGridView1.Rows[counter]
                        .Cells["Deposits"].Value.ToString());
                }
            }
        }

        // Iterate through the SelectedCells collection and sum up the values.
        for (counter = 0;
            counter < (DataGridView1.SelectedCells.Count); counter++)
        {
            if (DataGridView1.SelectedCells[counter].FormattedValueType ==
                Type.GetType("System.String"))
            {
                string value = null;

                // If the cell contains a value that has not been commited,
                // use the modified value.
                if (DataGridView1.IsCurrentCellDirty == true)
                {

                    value = DataGridView1.SelectedCells[counter]
                        .EditedFormattedValue.ToString();
                }
                else
                {
                    value = DataGridView1.SelectedCells[counter]
                        .FormattedValue.ToString();
                }
                if (value != null)
                {
                    // Ignore cells in the Description column.
                    if (DataGridView1.SelectedCells[counter].ColumnIndex !=
                        DataGridView1.Columns["Description"].Index)
                    {
                        if (value.Length != 0)
                        {
                            SelectedCellTotal += int.Parse(value);
                        }
                    }
                }
            }
        }

        // Set the labels to reflect the current state of the DataGridView.
        Label1.Text = "Withdrawals Total: " + WithdrawalTotal.ToString();
        Label2.Text = "Deposits Total: " + DepositTotal.ToString();
        Label3.Text = "Selected Cells Total: " + SelectedCellTotal.ToString();
        Label4.Text = "Total entries: " + DataGridView1.RowCount.ToString();
    }

    private void DataGridView1_CellValidating(object sender,
        DataGridViewCellValidatingEventArgs e)
    {
        int testint;

        if (e.ColumnIndex != 0)
        {
            if (e.FormattedValue.ToString().Length != 0)
            {
                // Try to convert the cell value to an int.
                if (!int.TryParse(e.FormattedValue.ToString(), out testint))
                {
                    DataGridView1.Rows[e.RowIndex].ErrorText =
                        "Error: Invalid entry";
                    e.Cancel = true;
                }
            }
        }
    }

    private void DataGridView1_CellValidated(object sender,
        DataGridViewCellEventArgs e)
    {
        // Clear any error messages that may have been set in cell validation.
        DataGridView1.Rows[e.RowIndex].ErrorText = null;
    }

    private void DataGridView1_UserDeletingRow(object sender,
        DataGridViewRowCancelEventArgs e)
    {
        DataGridViewRow startingBalanceRow = DataGridView1.Rows[0];

        // Check if the Starting Balance row is included in the selected rows
        if (DataGridView1.SelectedRows.Contains(startingBalanceRow))
        {
            // Do not allow the user to delete the Starting Balance row.
            MessageBox.Show("Cannot delete Starting Balance row!");

            // Cancel the deletion if the Starting Balance row is included.
            e.Cancel = true;
        }
    }

}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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