求vb大神帮忙做一道题。要求；只需要要程序写出来，界面的截图；

基本思路，是把数字作为字符串处理，然后运算的时候，先把它截取成长度一定的（比如4位）若干段，分段转换成数字求和（要考虑进位），然后转换成字符，在连接起来输出：

界面如下：

代码如下：

Option Explicit

Private Sub Command1_Click()

Dim ssss As String

ssss = PPP(Text1.Text, Text2.Text)

Text3.Text = ssss

End Sub

'自定义函数求两个长整数之和

Private Function PPP(ByVal s1 As String, ByVal s2 As String) As String

Dim dd1() As String

Dim n1 As Integer

Dim dd2() As String

Dim n2 As Integer

Dim s As String

Dim i As Integer

Dim d1 As Integer

Dim d2 As Integer

Dim t As Integer

Dim j As Integer

Dim JinWei As Boolean

Dim K As Integer

Dim SS1 As String

Dim SS2 As String

If Len(s1) > Len(s2) Then

   SS1 = s1

   SS2 = s2

Else

   SS1 = s2

   SS2 = s1

End If

n1 = 0

s = SS1

Do While Len(s) > 4

   n1 = n1 + 1

   ReDim Preserve dd1(1 To n1) As String

   dd1(n1) = Right(s, 4)

   s = Left(s, Len(s) - 4)

Loop

n1 = n1 + 1

ReDim Preserve dd1(1 To n1) As String

dd1(n1) = s

n2 = 0

s = SS2

Do While Len(s) > 4

   n2 = n2 + 1

   ReDim Preserve dd2(1 To n2) As String

   dd2(n2) = Right(s, 4)

   s = Left(s, Len(s) - 4)

Loop

n2 = n2 + 1

ReDim Preserve dd2(1 To n2) As String

dd2(n2) = s

JinWei = False

K = 0

For i = 1 To n1

   K = K + 1

   If K > n2 Then Exit For

   If Not JinWei Then

      t = Val(dd1(i)) + Val(dd2(K))

   Else

      t = Val(dd1(i)) + Val(dd2(K)) + 1

   End If

   If Len(CStr(t)) > 4 Then

      JinWei = True

   Else

      JinWei = False

   End If

   dd1(i) = Right(CStr(t), 4)

Next i

If JinWei Then

   For i = n2 + 1 To n1

      If JinWei Then

         t = Val(dd1(i)) + 1

      Else

         t = Val(dd1(i))

      End If

      If Len(CStr(t)) > 4 Then

         JinWei = True

      Else

         JinWei = False

      End If

      dd1(i) = Right(CStr(t), 4)

   Next i

End If

PPP = ""

For i = n1 To 1 Step -1

   PPP = PPP & dd1(i)

Next i

If JinWei Then PPP = "1" & PPP

End Function