The document discusses three Windows Forms controls: ComboBox, ListBox, and CheckedListBox. ComboBox allows the user to select from preset choices or type their own text. ListBox displays multiple selectable text items. CheckedListBox presents checkable items in a list. Code examples are provided to add and remove items from each control, as well as retrieve the selected item.

2. • ComboBox is a combination TextBox with a drop-
down. Its drop-down list presents preset choices. The
user can type anything into the ComboBox.
Alternatively, he or she can select something from the
list.

4. private void button1_Click(object sender, EventArgs e)
{
if (comboBox1.SelectedItem.ToString() == "two")
MessageBox.Show( comboBox1.SelectedItem.ToString());
}

5. private void button1_Click(object sender, EventArgs e)
{ comboBox1.Items.Add(textBox3.Text); }
private void button2_Click(object sender, EventArgs e)
{ comboBox1.Items.RemoveAt(comboBox1.SelectedIndex); }
Inserting
items to
combobox
Remove
items from
combobox

6. • ListBox stores several text items. It can interact with
other controls, including Button controls. We use this
control in Windows Forms. In the example program it
interacts with two Buttons—through the Button Click
event handler.

7. • CheckedListBox presents several items in a list. Each
item is checkable—the user can check a box. The
CheckedListBox control in Windows Forms is a way to
make longer, dynamic checkable lists.

8. From:
• ListBox
• ComboBox
• CheckedListBox

10. private void button1_Click(object sender, EventArgs e)
{ checkedListBox1.Items.Add(textBox1.Text); }
private void button2_Click(object sender, EventArgs e)
{ checkedListBox1.Items.RemoveAt(checkedListBox1.SelectedIndex); }
private void button5_Click(object sender, EventArgs e)
{ comboBox1.Items.Add(textBox3.Text); }
private void button6_Click(object sender, EventArgs e)
{ comboBox1.Items.RemoveAt(comboBox1.SelectedIndex); }
private void button3_Click(object sender, EventArgs e)
{ listBox1.Items.Add(textBox2.Text); }
private void button4_Click(object sender, EventArgs e)
{ listBox1.Items.RemoveAt(listBox1.SelectedIndex); }

11. private void button8_Click(object sender, EventArgs e)
{
MessageBox.Show(checkedListBox1.SelectedItem.ToString()+'n'+
comboBox1.SelectedItem.ToString() + 'n' +
listBox1.SelectedItem.ToString());
}
private void button7_Click(object sender, EventArgs e)
{
Application.Exit();
}