Python:如何迭代嵌套在while循环中的列表

Question

我有以下代码：

shape = input("Please enter your choice of shape? ")    
nthTime = ["second","third","fourth","fifth","sixth"]
while shape.lower() not in ["octagon","heptagon","hexagon"] :
    print("Please select a shape from the list!")
    shape = input("Pick a shape, for the " + nthTime + " time! ")

我如何才能实现这样的结果，Python每次通过while循环时都会迭代列表"nthTime"？

我可以使用嵌套的for循环，但这当然会运行整个列表，这不是我的目标。

因此，我得出结论，我需要使用嵌套的while循环；但是我搞不清楚确切的语法。

我希望这个问题将来也能对其他人有用。

Answer 1

只有当用户输入正确的值时，才使用for循环并中断循环

for iteration in nthTime:
    if shape.lower() not in ["octagon","heptagon","hexagon"]:
        print("Please select a shape from the list!")
        shape = input("Pick a shape, for the " + iteration + " time! ")
    else: break
else: print "You have wasted all your chances, try again later"

Answer 2

类似这样的东西：

shape = input("Please enter your choice of shape? ")    
nthTime = ["second","third","fourth","fifth","sixth"]
undesired_shapes = ["octagon","heptagon","hexagon"]
indx = 0
while shape.lower() not in undesired_shapes:
    print("Please select a shape from the list!")
    shape = input("Pick a shape, for the " + nthTime[indx] + " time! ")
    indx += 1
    if indx >= len(nthTime):
        print 'Giving up !!'
        break

Answer 3

nthTime.reverse()
while shape.lower() not in ["octagon","heptagon","hexagon"] and nthTime:
    print("Please select a shape from the list!")
    shape = input("Pick a shape, for the " + nthTime.pop() + " time! ")