exit for用法,该怎么处理

exit for用法
For i = NIP To NIP1
            For j = jstart To flen - 1
                If Abs(X1(i) - Xbgt(j)) < 0.000001 Then
               y1(i) = Ybgt(j)
                   'JSTART% = J% - 1
                   If i < NIP + 5 Then
                      jstart = nxmax
                   ElseIf i < NIP1 - 5 Then
                      jstart = j - 1
                   Else
                      jstart = nxmax
                   End If
                   Exit For
                ElseIf X1(i) > Xbgt(j + 1) And X1(i) < Xbgt(j) Then
                       kk = (Ybgt(j) - Ybgt(j + 1)) / (Xbgt(j) - Xbgt(j + 1))
                   y1(i) = Ybgt(j) + kk * (X1(i) - Xbgt(j + 1))
                       'JSTART% = J% - 1
                       If i < NIP + 5 Then
                          jstart = nxmax
                       ElseIf i < NIP1 - 5 Then
                          jstart = j - 1
                       Else
                          jstart = nxmax
                       End If
                       Exit For