编写程序，实现对任意字符串的加密和解密操作

Dim a() As String, b() As Integer, n As Integer
Text2 = ""
n = Len(Text1)
ReDim a(n)
ReDim b(n + 3)
For i = 1 To n
a(i) = Mid(Text1, i, 1)
If (Asc(a(i)) >= 65 And Asc(a(i)) <= 90) Or (Asc(a(i)) >= 97 And Asc(a(i)) <= 122) Then
b(i) = Asc(a(i)) + 3
If b(i) > Asc("Z") And b(i) < Asc("a") Then b(i) = Asc("A") + b(i) - Asc("Z") - 1
If b(i) > Asc("z") Then b(i) = Asc("a") + b(i) - Asc("z") - 1
Else
b(i) = Asc(a(i))
End If

a(i) = Chr(b(i))
Text2 = Text2 & a(i)
Next
Text3 = Text2
End Sub
Private Sub Command2_Click()
Dim a() As String, b() As Integer, n As Integer
Text4 = ""
n = Len(Text3)
ReDim a(n)
ReDim b(n + 3)
For i = 1 To n
a(i) = Mid(Text3, i, 1)
If (Asc(a(i)) >= 65 And Asc(a(i)) <= 90) Or (Asc(a(i)) >= 97 And Asc(a(i)) <= 122) Then
b(i) = Asc(a(i)) - 3
If b(i) >= 62 And b(i) < Asc("A") Then b(i) = Asc("Z") - (Asc("A") + b(i)) + 1
If b(i) >= 94 And b(i) < Asc("a") Then b(i) = Asc("z") - Asc("a") + b(i) + 1
Else
b(i) = Asc(a(i))
End If
a(i) = Chr(b(i))
Text4 = Text4 & a(i)
Next
End Sub
为便于调试对照，其中将加密后的文件直接放在了TEXT3中。调试完可去掉