众多语言中都有if else这对条件选择组合，但是在python中还有更多else使用的地方，比如说循环for，或者while都可以和else组合。
下面简单介绍一下for-else while-else组合
循环组合中的else执行的情况下是循环正常结束（即不是使用break退出）。如下列代码：
numbers = [1,2,3,4,5] for n in numbers: if (n > 5): print('the value is %d '%(n)) breakelse: print('the for loop does not end with break') i = 0while(numbers[i] < 5): print('the index %d value is %d'%(i, numbers[i])) if (numbers[i] < 0) : break i = i + 1else: print('the loop does not end with break') numbers = [1,2,3,4,5]for n in numbers: if (n > 5): print('the value is %d '%(n)) breakelse: print('the for loop does not end with break') i = 0while(numbers[i] < 5): print('the index %d value is %d'%(i, numbers[i])) if (numbers[i] < 0) : break i = i + 1else: print('the loop does not end with break')执行结果如下：
C:Python27>python.exe for_else.py the for loop does not end with breakthe index 0 value is 1the index 1 value is 2the index 2 value is 3the index 3 value is 4the loop does not end with break
