请问各位高手一个问题

Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim len1 As Integer
Dim a, c As String

a = Trim(TextBox1.Text)
len1 = Len(a)
For i As Integer = 0 To len1 - 1
c = c & Mid(a, len1 - i, 1)
Label1.Text = c

Next i
End Sub
End Class
没有加for循环时正确但是加上后就出现问题请问该如何改啊

Dim len1 As Integer
Dim a, c As String
c = ""
a = Trim(TextBox1.Text)
len1 = Len(a)
For i As Integer = 0 To len1 - 1
c = c & Mid(a, len1 - i, 1)
Next i
Label1.Text = c

多谢楼主

变量Ｃ在引用之前为什么得先赋＂＂啊

C如果之前不赋值,len1 如果是零的话C就会产生为空,如果是VB就不用赋,因为VB默认的就""来的.

谢谢了楼主

For i As Integer = 0 To len1 - 1
c = c & Mid(a, len1 - i, 1)
Label1.Text += c

Next i

这样也行的