大数加法。在文本框Text1和Text2中输入两个大数，点击“相加”按钮后，在文本框Text3中输出结果。
实现上述功能的VB程序如下，请在划线处填入合适的代码。
Private Sub Command1_Click()
Dim s1 As String
Dim s2 As String
Dim s3 As String
Dim l1 As Integer
Dim l2 As Integer
Dim l3 As Integer
Dim a(1 To 100) As Integer
Dim b(1 To 100) As Integer
Dim c(1 To 100) As Integer
Dim t As Integer
s1 = Text1.Text
s2 = Text2.Text
l1 = Len(s1)
l2 = Len(s2)
For i = l1 To 1 Step -1
a(i) ={#blank#}1{#/blank#}
Next
For i = l2 To 1 Step -1
b(i) =Val(Mid(s2, l2 - i + 1, 1))
Next
If l1 > l2 Then l3 =
l1 Else l3 = l2
t = 0
For i = 1 To l3
c(i) = a(i) + b(i) + t
t = c(i) \ 10
c(i) ={#blank#}2{#/blank#}
Next
For i = 1 To l3
s3 = Str(c(i)) + s3
Next
If{#blank#}3{#/blank#}Then s3 = “1” + s3
Text3.Text = s3
End Sub
