exit for 怎么连跳两级for each 了？好奇怪！！

[lmhcs]

今天调试下程序时，忽然发现，exit for 一下子跳出两层的for。eixt for 不是只跳所在的那一层而已吗？蒙了。见下面代码

            '筛选符合条件
            For Each s As String In arr   'for1
                If String.IsNullOrEmpty(s) Then Continue For
                Dim nextFiller As Boolean = False
                For Each b As fhBuilding In buildings   'for2
                    If nextFiller Then
                        nextFiller = False
                        Exit For
                    End If
                    For Each r As fhRoom In b.Rooms   'for3
                        If String.Equals(s, r.FullName, StringComparison.OrdinalIgnoreCase) Then
                            _VisRooms.Add(r)
                            nextFiller = True
                            Exit For   '为什么exit for 不是离开for3 而是离开for2，直接跳到for1呢？ 
                        End If
                    Next
                Next
            Next

为了验证exit for 跳跃能力，特写了下面代码，发现exit for 就只能跳出所在的for 层，但为什么上面代码一下子跳出两层呢？

  Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Dim a1() As Integer = New Integer() {1, 2, 3, 4, 5}
        Dim a2() As Integer = New Integer() {11, 12, 13, 14, 15}
        Dim a3() As Integer = New Integer() {21, 22, 23, 24, 25}
        Dim a4() As Integer = New Integer() {31, 32, 33, 34, 35}
        Dim a5() As Integer = New Integer() {41, 42, 43, 44, 45}
        For Each i1 As Integer In a1
            For Each i2 As Integer In a2
                For Each i3 As Integer In a3
                    For Each i4 As Integer In a4
                        For Each i5 As Integer In a5
                            Console.WriteLine(i5)
                            If i5 = 42 Then
                                Exit For
                            End If
                        Next
                    Next
                Next
            Next
        Next
    End Sub

[良朋]

5楼详细地给了你答案

[智者知已应修善业]

跟踪一下查看各变量和条件,或许上层刚好结束了?

[智者知已应修善业]

从第三循环看改变了第二循环的BOOL变量,因此直接跳出2层. 可以逐层调试跟踪,总会找到问题所在.

[正怒月神]

VB不熟悉，但是有没有类似GO的语法呢？

[eaqpi]

nextFiller = True

[stherix]

因为跳出之前 设置了 nextFiller = True 而在for2里面判断nextFiller 为 True会继续跳出

[智者知已应修善业]

我看见一个奇怪现象就是邀请回答往往出现404第二天再看又有,但有的也是打不开的网址. 每循环打断点应该可以看到第三层跳出后第二层还应该循环判断一下才跳出,貌似连续跳出2层循环,这完全是设计的逻辑问题.

[jhonsonzhang]

For Each s As String In arr 'for1
If String.IsNullOrEmpty(s) Then Continue For
Dim nextFiller As Boolean = False
For Each b As fhBuilding In buildings 'for2
If nextFiller Then
nextFiller = False
Exit For
End If
dim tpFiller=false
For Each r As fhRoom In b.Rooms 'for3
If String.Equals(s, r.FullName, StringComparison.OrdinalIgnoreCase) Then
_VisRooms.Add(r)
tpFiller = True
Exit For '为什么exit for 不是离开for3 而是离开for2，直接跳到for1呢？
End If
Next
nextfiller=tpfiller
Next
Next

这下就不会exit 到for1 了。但这代码太冗余了，用linq lamada应该2行就解决了。看着还不头疼。

[轻鸿万里]

引用 楼主 lmhcs 的回复:

今天调试下程序时，忽然发现，exit for 一下子跳出两层的for。eixt for 不是只跳所在的那一层而已吗？蒙了。见下面代码

            '筛选符合条件
            For Each s As String In arr   'for1
                If String.IsNullOrEmpty(s) Then Continue For
                Dim nextFiller As Boolean = False
                For Each b As fhBuilding In buildings   'for2
                    If nextFiller Then
                        nextFiller = False
                        Exit For
                    End If
                    For Each r As fhRoom In b.Rooms   'for3
                        If String.Equals(s, r.FullName, StringComparison.OrdinalIgnoreCase) Then
                            _VisRooms.Add(r)
                            nextFiller = True
                            Exit For   '为什么exit for 不是离开for3 而是离开for2，直接跳到for1呢？ 
                        End If
                    Next
                Next
            Next

为了验证exit for 跳跃能力，特写了下面代码，发现exit for 就只能跳出所在的for 层，但为什么上面代码一下子跳出两层呢？

  Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Dim a1() As Integer = New Integer() {1, 2, 3, 4, 5}
        Dim a2() As Integer = New Integer() {11, 12, 13, 14, 15}
        Dim a3() As Integer = New Integer() {21, 22, 23, 24, 25}
        Dim a4() As Integer = New Integer() {31, 32, 33, 34, 35}
        Dim a5() As Integer = New Integer() {41, 42, 43, 44, 45}
        For Each i1 As Integer In a1
            For Each i2 As Integer In a2
                For Each i3 As Integer In a3
                    For Each i4 As Integer In a4
                        For Each i5 As Integer In a5
                            Console.WriteLine(i5)
                            If i5 = 42 Then
                                Exit For
                            End If
                        Next
                    Next
                Next
            Next
        Next
    End Sub

关键是你for2 是判断 nextFiller = True就退出循环，而你for3赋值了 nextFiller = True才退出，所以连for2也退出了。

[秋天之落叶]

经验告诉我们，这种情况绝对是循环逻辑写的问题，因为VB不可能出现这样的基本错误，哈哈

[haisumchen]

问题出在这里吧？If nextFiller Then