核心代码:

'只允许输入数字、"."

Private Sub txtField_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtField0.KeyPress, txtField1.KeyPress, txtField2.KeyPress, txtField3.KeyPress

If e.KeyChar = "." Then

Dim tx As TextBox = CType(sender, TextBox)

'最后的文本框不可以输入"."

'在其它文本框输入"."，相当于输入"Tab"键，即光标到下一文本框

If tx.Text = "" Or tx.SelectedText <> "" Then

e.Handled = True

End If

If tx.Name <> "txtField3" Then

SendKeys.Send("{TAB}")

Else

'最后的文本框不可以输入"."

e.Handled = True

End If

ElseIf (Not IsNumeric(e.KeyChar)) And e.KeyChar <> ControlChars.Back Then

e.Handled = True

Else

Dim tx As TextBox = CType(sender, TextBox)

If (Len(tx.Text) = 2 And e.KeyChar <> ControlChars.Back And tx.SelectedText.Length = 0) Then

If tx.Name <> "txtField3" Then

SendKeys.Send("{TAB}")

End If

End If

End If

'控制ControlChars.Back退格键

Dim tx1 As TextBox = CType(sender, TextBox)

If (Len(tx1.Text) = 0 And e.KeyChar = ControlChars.Back) Then

Select Case tx1.Name

Case "txtField3"

If txtField3.Text = "" Then

txtField2.Focus()

End If

Case "txtField2"

If txtField2.Text = "" Then

txtField1.Focus()

End If

Case "txtField1"

If txtField1.Text = "" Then

txtField0.Focus()

End If

End Select

End If

End Sub

当运行时：

当出现错误时：