Public Class Form1

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

ListBox1.Items.Add(1234)‘按行增加数据

ListBox1.Items.Add(2345)

ListBox1.Items.Add("刘珊")

ListBox1.Items.Add("女女")

' ListBox1.Items.Clear()’清除所有数据

ListBox1.Items.Add(4)

ListBox1.Items.Add(5)

ListBox1.Items.Add(6)

End Sub

Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged

TextBox1.Text = ListBox1.SelectedItem'选中listbox1 的数据，并在txt文档框显示

End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click

Dim A As Integer, B As Integer

If TextBox2.Text.Length > 0 Then '判断是否有输入，如果没输入提示请输入数据

A = CInt(TextBox2.Text) * 6

B = TextBox2.Text * 6

MessageBox.Show(A)

Else

MessageBox.Show("请输入数据")

Exit Sub

End If

MessageBox.Show(B)

TextBox3.Text = 5

End Sub

End Class

文章重点在于表达 字符串与数字格式的转换

CDbl() 将字符串数字转换为Double类型的数字

CInt () 将字符串数字转换为Integer类型的数字

CStr() 将数字转换为数字的字符串