VB编程;摄氏温度转换为华氏温度,当输入其它格式时要报错,怎么编程呀?谢谢急需!!!!

设一个command
Private Sub Command1_Click()
Dim a As Double
a=Val(Text1.Text)
If a=0 Then
Msgbox("错误","Err",vbokonly)
else
Label1.Caption=a*1.8+32
End If
End Sub

假定你的数据输入容器为Text1,则将text1的KeyPress事件代码修改如下:
Private Sub Text1_KeyPress(KeyAscii As Integer)
If (KeyAscii <> 8) And (KeyAscii <> 13) And (KeyAscii < 48) Or (KeyAscii > 57) Then
'忽略退格键,回车键和数字键,其它按键提示错误
MsgBox "请输入数字", vbExclamation, "输入错误"
KeyAscii = 0
End If
End Sub