眾多語言中都有if else這對條件選擇組合，但是在python中還有更多else使用的地方，比如說循環for，或者while都可以和else組合。
下面簡單介紹一下for-else while-else組合
循環組合中的else執行的情況下是循環正常結束（即不是使用break退出）。如下列代碼：
numbers = [1,2,3,4,5]
for n in numbers:
if (n > 5):
print('the value is %d '%(n))
break
else:
print('the for loop does not end with break')
i = 0
while(numbers[i] < 5):
print('the index %d value is %d'%(i, numbers[i]))
if (numbers[i] < 0) :
break
i = i + 1
else:
print('the loop does not end with break')
執行結果如下：
C:\Python27>python.exe for_else.py
the for loop does not end with break
the index 0 value is 1
the index 1 value is 2
the index 2 value is 3
the index 3 value is 4
the loop does not end with break
