Private Sub Form_Click()
  Dim length As Integer
       Dim str1 As String
       Dim strleft As String
       Dim strright As String
       Dim k As Integer
       str1 = InputBox("请输入任意的字符串") '输入任意字符串
       length = Len(Trim(str1))
       k = 1
       Do
               strleft = Mid(str1, k, 1) '从左边起逐个取出一个字符
               strright = Mid(str1, length + 1 - k, 1) '从右边起逐个取出一个字符
               If strleft <> strright Then
                       Exit Do
               End If
               k = k + 1
       Loop While k <= length / 2
       If k > length / 2 Then
               Form1.Print str1 & "是回文"
       Else
               Form1.Print str1 & "不是回文"
       End If
End Sub

回文：左边开始读和右边开始读都相同
例：yyuuyy