今天由于试验一个数据，没有采取递归方法，做了一个简单的笨笨的字符串组合程序， 设了一个退出标志
stopflag 为true时跳出循环，可程序就是不跳出，所以造成窗体退不出，大家给看看，问题出在哪里？
Option Explicit
Private StopFlag As Boolean
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
Private val As Long
Private prN As Integer
Private Const Str = "abcdefghijklmnopqrstuvwxyz1234567890"
Private Sub Command1_Click()
Dim i As Integer
Dim ii As Integer
Dim iii As Integer
Dim iiii As Integer
Dim iiiii As Integer
Dim n As Integer
Dim s As String
Dim s1 As String
Dim L As Integer
L = Len(Str)
prN = 1
If StopFlag Then
If prN <> 1 Then
prN = txtN
Else
prN = 1
End If
End If
s = ""
StopFlag = False
For iiiii = 1 To L
txti(4) = iiiii
For iiii = 1 To L
txti(3) = iiii
For iii = 1 To L
txti(2) = iii
For ii = 1 To L
txti(1) = ii
For i = 1 To L
Select Case prN
Case 1: s = Mid(Str, i, 1)
Case 2: s = Mid(Str, ii, 1) & Mid(Str, i, 1)
Case 3: s = Mid(Str, iii, 1) & Mid(Str, ii, 1) & Mid(Str, i, 1)
Case 4: s = Mid(Str, iiii, 1) & Mid(Str, iii, 1) & Mid(Str, ii, 1) & Mid(Str, i, 1)
Case 5: s = Mid(Str, iiiii, 1) & Mid(Str, iiii, 1) & Mid(Str, iii, 1) & Mid(Str, ii, 1) & Mid(Str, i, 1)
End Select
'Call ShowResults(s) 这里的过程我注释掉也不行
txti(0) = i
prN = 1
If StopFlag Then GoTo Exit_ '发现StopFlag的值不改变
DoEvents '后来加了一个这个
Next
prN = 2
Next
prN = 3
Next
prN = 4
Next
prN = 5
Next
Exit Sub
Exit_:
prN = 99 '这里设了个值是为了检查这个值的变化
End Sub
Private Sub Command2_Click()
StopFlag = True
End Sub
Private Sub Command3_Click()
StopFlag = False
End Sub
Private Sub Command4_Click()
StopFlag = True
n = 1
End Sub
'主要是下面这个过程
Private Sub Command5_Click()
StopFlag = True ‘停止循环标志
Sleep (5000) '后来加了一个延时 也不行
Unload Me
End Sub
Private Sub Form_Load()
prN = 1
StopFlag = False
End Sub
