如何把这段VB代码写成一个函数，供其他对象调用？

'你的代码里面的Str()改成Chr()

Function RestText(KeyAscii As Integer) As Integer
Select Case Chr(KeyAscii) '多分枝用Select case 语句比较好
Case 0 To 9 '如果按键在 0-9 之间 或者
Case ".", "-", Chr(8) '按下小数点，负号，或者删除键BackScape键则不执行特殊操作
Case Else
KeyAscii = 0 '取消本次按键事件。
Beep '提示输入错误
End Select
RestText = KeyAscii
End Function

Private Sub Text1_KeyPress(KeyAscii As Integer)
KeyAscii = RestText(KeyAscii)
End Sub

sub a(KeyAscii as integer)
Select Case Str(KeyAscii) '多分枝用Select case 语句比较好
Case KeyAscii > Asc("0") And KeyAscii < Asc("9") '如果按键在 0-9 之间 或者
Case ".", "-", Str(8) '按下小数点，负号，或者删除键BackScape键则不执行特殊操作
Case Else
KeyAscii = 0 '取消本次按键事件。
Beep '提示输入错误
End Select
end sub

function IsNum(KeyAscii as integer) as integer

Select Case Str(KeyAscii) '多分枝用Select case 语