如何訪問不同潛艇中的不同變量？

Question

我一直在試圖在Visual Studio 2012 Ultimate上做一個計算器。我一直在嘗試創建不同的按鈕，一個請求第一個號碼，第二個請求第二個號碼，第三個請求操作員，最後一個在消息框中顯示答案。但是，每當我嘗試從另一個子集調用整數時，它都不起作用。我已經嘗試製作Sub Public。這裏是我的代碼：

Public Class Form1 

    Public Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
     Dim prompt1, title1 As String 
     Dim a As Integer 
     prompt1 = "Enter First Number : " 
     title1 = "First Number" 
     a = InputBox(prompt1, title1) 
    End Sub 

    Public Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click 
     Dim prompt2, title2 As String 
     Dim b As Integer 
     prompt2 = "Enter Second Number : " 
     title2 = "Second Number" 
     b = InputBox(prompt2, title2) 
    End Sub 

    Public Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click 
     Dim prompt3, title3 As String 
     Dim op As String 
     Dim ans As Integer 
     prompt3 = "Enter Operator : " 
     title3 = "Operator" 
     op = InputBox(prompt3, title3) 
     If op = "+" Then 
      ans = a + 
     End If 


    End Sub 

    Public Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click 


    End Sub 
End Class 

正如你可以看到我已經沒有完成它，因爲我不能在第三個按鈕調用。

任何想法？

如果我搞砸了，請指出。

Answer 1

定義變量的按鈕1

Public Class Form1 
    Dim a As Integer 
Public Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
Dim prompt1, title1 As String 
prompt1 = "Enter First Number : " 
title1 = "First Number" 
a = InputBox(prompt1, title1) 
End Sub 

一個外面現在你可以使用變量a