Button
The Button fires a Click event. Double-click it in the designer to auto-generate the handler. Key properties: Text, BackColor, ForeColor, Font, Enabled.
Button click
ButtonClick.cs
private void btnSubmit_Click(object sender, EventArgs e)
{
string name = txtName.Text.Trim();
if (string.IsNullOrEmpty(name))
{
MessageBox.Show("Please enter your name.", "Validation",
MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
lblGreeting.Text = $"Hello, {name}!";
}TextBox
Key TextBox properties: Text, Multiline, PasswordChar, MaxLength, ReadOnly. The TextChanged event fires every time the text changes.
ListBox & ComboBox
Add items with Items.Add() or at design time. The SelectedItem property returns the selected object; SelectedIndex returns its position. ComboBox combines a text box with a drop-down list.
ListBox example
ListBoxDemo.cs
// Populate at runtime
listBox1.Items.AddRange(new[] { "Apple", "Banana", "Cherry" });
// Handle selection
private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
lblSelection.Text = $"Selected: {listBox1.SelectedItem}";
}CheckBox & RadioButton
CheckBox.Checked returns a bool. Group RadioButtons inside a GroupBox or Panel—only one in the group can be checked at a time.
CheckBox usage
CheckDemo.cs
private void btnApply_Click(object sender, EventArgs e)
{
var sb = new System.Text.StringBuilder();
if (chkBold.Checked) sb.Append("Bold ");
if (chkItalic.Checked) sb.Append("Italic ");
if (chkUnder.Checked) sb.Append("Underline");
lblStyle.Text = sb.ToString();
}