Question

所以我只是在python3上写了一个基本的英里到公里转换器。它会询问您是否要在键入nautical时将海里或陆地英里转换为km，然后转到该循环并将海里转换为km。土地也是如此，如果您输入土地，它将土地英里转换为公里。但是问题是当我键入其他内容而不是航海或着陆时，程序崩溃了。我该如何写写“请仅在此输入中写上航海或陆地”的代码。当我在“要转换为公里数的英里数”中键入一个非数字的输入时，会发生相同的情况它崩溃了...

print("Hello! This is a mile to km converter")
print("Do you want to convert nauitcal miles or land miles?")

question_convert = input("Please type nautical or land \n")

if question_convert == "nautical":
NAUTICAL = True

if question_convert == "land":
    NAUTICAL = False

while True:
    while NAUTICAL == True:
        nautical_mile = 1.852
        print("How many nauitical miles do you want to convert in km?")
        convert_nauitcal = float(input())
        converted_nautical = float(convert_nauitcal * nautical_mile)
        print("Here's your converted nauitical miles: ")
        print(converted_nautical)
        quit()

    while NAUTICAL == False:
        land_mile = 1.609344
        print("How many land miles do you want to convert in km?")
        convert_land = float(input())
        converted_land = float(convert_land * land_mile)
        print("Here's your converted land miles: ")
        print(converted_land)
        quit()

#land_mile = 1.609344
#nautical_mile = 1.852

Answer 1

我将对其进行更改，并将问题部分也放入while语句内，以便您的用户只有输入有效的响应后才能继续操作。因此，调整后的代码如下：

print("Hello! This is a mile to km converter")
print("Do you want to convert nauitcal miles or land miles?")

valid_input=False
while not valid_input:
    question_convert = input("Please type nautical or land \n")
    if question_convert == "nautical":
        NAUTICAL = True
        valid_input=True
    if question_convert == "land":
        NAUTICAL = False
        valid_input=True

while True:
    while NAUTICAL == True:
        nautical_mile = 1.852
        print("How many nauitical miles do you want to convert in km?")
        convert_nauitcal = float(input())
        converted_nautical = float(convert_nauitcal * nautical_mile)
        print("Here's your converted nauitical miles: ")
        print(converted_nautical)
        quit()

    while NAUTICAL == False:
        land_mile = 1.609344
        print("How many land miles do you want to convert in km?")
        convert_land = float(input())
        converted_land = float(convert_land * land_mile)
        print("Here's your converted land miles: ")
        print(converted_land)
        quit()

Answer 2

这是因为您将其放入无限的while循环中。您可以通过修改if既不是NAUTICAL也不是True的初始False条件来解决此问题：

print("Hello! This is a mile to km converter")
print("Do you want to convert nauitcal miles or land miles?")

question_convert = input("Please type nautical or land \n")

NAUTICAL = None
if question_convert == "nautical":
    NAUTICAL = True    
else if question_convert == "land":
    NAUTICAL = False
else:
    print("I don't understand that...")
    # maybe throw an exception here if you want, instead of exit()-ing
    exit()

while NAUTICAL is not None:
    while NAUTICAL:
        nautical_mile = 1.852
        print("How many nauitical miles do you want to convert in km?")
        convert_nauitcal = float(input())
        converted_nautical = float(convert_nauitcal * nautical_mile)
        print("Here's your converted nauitical miles: ")
        print(converted_nautical)
        quit()

    while not NAUTICAL:
        land_mile = 1.609344
        print("How many land miles do you want to convert in km?")
        convert_land = float(input())
        converted_land = float(convert_land * land_mile)
        print("Here's your converted land miles: ")
        print(converted_land)
        quit()

#land_mile = 1.609344
#nautical_mile = 1.852

Answer 3

对于您的第一个输入问题，可能会崩溃，因为除非输入是“航海”或“陆地”，否则未定义变量NAUTICAL。

一个解决这个问题的方法是

if question_convert=='nautical':
   NAUTICAL = True
elif question_convert=='land':
   NAUTICAL = False
else:
   print('Please type land or nautical!!')
   sys.exit(1)

对于其他输入验证问题，在这种情况下检查数字输入的最简单方法是在float转换周围使用try / except子句

...
in_val = input()
try:
   converted_land = float(in_val)
except ValueError:
   print("{} doesn't look like a number!!".format(inv_val))
   # might want to exit at this point or use a default value for converted_land
...

Answer 4

ALLOWED_TYPES = {'nautical', 'land'}    

question_convert = ''

while question_convert not in ALLOWED_TYPES:

    question_convert = input("Please type nautical or land \n")

    if question_convert not in ALLOWED_TYPES:

        print('"Please only write nautical or land in this input')
        continue

    if question_convert == "nautical":
        NAUTICAL = True

    if question_convert == "land":
        NAUTICAL = False

Python3我希望if语句仅适用于2条语句

4 个答案: