文本框与数据校验
即与文本框相关的事件。
练习：试做一个字处理软件，包括如下功能：输入内容；打开、保存文件；编辑功能（复制、剪切、粘贴）；文字格式设置（字体、字号、字形、字的颜色）。
6．5复选框、单选按钮（相关vb.net教程)
复选框：可以多选与不选，灵活。
单选按钮：选且只能选择一个。
习惯通过groupbox控件结合成一组。
Checkbox: 复选框
常用属性
Checked:复选框是否被选择．
Appearance:外观样式，normal—常规外观，button—按钮外观
Flatstyle:外观风格，有四个．
常用事件：click—单击、CheckedChanged—选择变化激发的。
Radiobutton: 单选按钮
Groupbox: 控件组，用以组织控件成为一组．
应用：
例4：在文本框中输入文字，然后用单选钮控制字的颜色、字型(文字加粗、倾斜、下画线)字号（10、20、40）。[实验报告21 ]
见字体字号字形字的颜色．
注意：字的颜色可以在程序直接设置属性实现，但字号，字型则不能直接在程序中设置？（因为它们都是只读属性，只能在属性窗口中设置，而不能在程序中引用）
程序为：
  Private Sub setfont()
        Dim s As FontStyle = FontStyle.Regular
        If CheckBox1.Checked Then s = s + FontStyle.Bold
        If CheckBox2.Checked Then s = s + FontStyle.Italic
        If CheckBox3.Checked Then s = s + FontStyle.Underline
        TextBox1.Font = New Font(TextBox1.Font.Name, TextBox1.Font.Size, s)
    End Sub
    Private Sub setsize()
        If RadioButton1.Checked Then TextBox1.Font = New Font(TextBox1.Font.Name, 10)
        If RadioButton2.Checked Then TextBox1.Font = New Font(TextBox1.Font.Name, 20)
        If RadioButton3.Checked Then TextBox1.Font = New Font(TextBox1.Font.Name, 40)
    End Sub
 
    Private Sub RadioButton1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton1.CheckedChanged
        setsize()
    End Sub
 
    Private Sub RadioButton6_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton6.CheckedChanged
        TextBox1.ForeColor = Color.Black
    End Sub
 
    Private Sub RadioButton5_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton5.CheckedChanged
        TextBox1.ForeColor = Color.Red
    End Sub
 
    Private Sub RadioButton4_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton4.CheckedChanged
        TextBox1.ForeColor = Color.Blue
    End Sub
 
    Private Sub RadioButton2_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton2.CheckedChanged
        setsize()
    End Sub
 
    Private Sub RadioButton3_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton3.CheckedChanged
        setsize()
    End Sub
 
    Private Sub CheckBox1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox1.Click
        setfont()
    End Sub
 
    Private Sub CheckBox2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox2.Click
        setfont()
    End Sub
 
    Private Sub CheckBox3_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox3.Click
        setfont()
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        End
    End Sub