Question

我是Python初学者，并尝试首次使用try和except。我在问用户一个整数值，但是我不想一次又一次地问用户，直到给出整数为止，而不是结束该程序（如果用户输入了一个字符串）。

此刻，仅询问用户一次是否提供字符串，但如果再次输入错误，程序就会停止。

下面是我的意思的一个例子。

我在Stackoverflow上浏览了类似的问题，但是我无法通过任何建议对其进行修复。

travel_score = 0

while True:
    try:
        travel_score = int(input("How many times per year do you travel? Please give an integer number"))
    except ValueError:
        travel_score = int(input("This was not a valid input please try again"))


print ("User travels per year:", travel_score)

Answer 1

问题在于，一旦抛出ValueError异常，它就会被捕获在except块中，但是如果再次抛出该异常，将不再有except来捕获这些异常新错误。解决方案是仅在try块中转换答案，而不是在给出用户输入后立即转换。

尝试一下：

travel_score = 0
is_int = False
answer = input("How many times per year do you travel? Please give an integer number: ")

while not is_int:    
    try:
        answer = int(answer)
        is_int = True
        travel_score = answer
    except ValueError:
        answer = input("This was not a valid input please try again: ")


print ("User travels per year:", travel_score)

Answer 2

问题是您的第二个输入没有异常处理。

travel_score = 0

while True:
    try:
        travel_score = int(input("How many times per year do you travel? Please give an integer number"))
    except ValueError:
        # if an exception raised here it propagates
        travel_score = int(input("This was not a valid input please try again"))


print ("User travels per year:", travel_score)

处理此问题的最佳方法是，如果用户输入无效，则向其发送信息性消息，并允许循环返回到开头并以这种方式重新提示：

# there is no need to instantiate the travel_score variable
while True:
    try:
        travel_score = int(input("How many times per year do you travel? Please give an integer number"))
    except ValueError:
        print("This was not a valid input please try again")
    else:
        break  # <-- if the user inputs a valid score, this will break the input loop

print ("User travels per year:", travel_score)

Answer 3

@Luca Bezerras的回答很好，但是您可以使其更加紧凑：

_id:ObjectId("111111111111111111111112")
name: "Honda Civic" (String value)

如何在while循环中使用try-except命令询问用户输入

3 个答案: