計算機(jī)等級考試二級VB常用算法(10)：字符處理

1、算法說明
    1) 加密解密
    最簡單的加密方法是：將每個字母加一序數(shù)，例如5，這時：
    “A”→”F”,”a” →”f”,”B” →”G”,”b” →”g”……”Y” →”D”, ”y” →”d”,”Z” →”E”, ”z” →”e”
    解密是加密的逆操作。
    代碼如下：
     Option Explicit
     Private Sub Command1_Click()
     Dim strInput$, Code$, Record$, c As String * 1
     Dim i%, length%, iAsc%
     strInput = Text1.Text
     length = Len(Trim(strInput))
     Code = ""
     For i = 1 To length
     c = mid(strInput, i, 1)
     Select Case c
     Case "A" To "Z"
     iAsc = Asc(c) + 5
     If iAsc > Asc("Z") Then iAsc = iAsc - 26
     Code = Code & Chr(iAsc)
     Case "a" To "z"
     iAsc = Asc(c) + 5
     If iAsc > Asc("z") Then iAsc = iAsc - 26
     Code = Code & Chr(iAsc)
     Case Else
     Code = Code & c
     End Select
     Next i
     Text2.Text = Code
     End Sub
     Private Sub Command3_Click()
     Text1.Text = ""
     Text2.Text = ""
     Text3.Text = ""
     Text1.SetFocus
     End Sub