如何使用户输入更改布尔值？

Question

I am trying to make a simple little program using Python 3.7.4. I was wondering if it is possible (If so, how?) to change the Boolean value of a variable from a user input.

As you can see in the attached code, I have tried putting the append in quotations. I also tried no quotations.

    is_male = []
    is_female = []
    is_tall = []
    is_short = []

    ans_male = bool(input("Are you a male? (True or False): "))
    if ans_male == "True":
        is_male.append("True")
    if ans_male == "False":
        is_male.append("False")
    ans_female = bool(input("Are you a female? (True or False): "))
    if ans_female == "True":
        is_female.append("True")
    if ans_female == "False":
        is_female.append("False")
    ans_tall = bool(input("Are you tall? (True or False): "))
    if ans_tall == "True":
        is_tall.append("True")
    if ans_tall == "False":
        is_tall.append("False")
    ans_short = bool(input("Are you short? (True or False): "))
    if ans_short == "True":
        is_short.append("True")
    if ans_short == "False":
        is_short.append("False")

I expect the is_male, is_tall, etc. variable's value to change to True or False according to the input.

Answer 1

You are getting a few things wrong.

1) When transforming a string into a boolean, python always returns True unless the string is empty ( "" ). So it doesn't matter if the string is "True" or "False" , it will always become True when you do bool(str) .

2) In your if statements, you're comparing a boolean (the ans_male variable) with a string ( "True" ). If you want to work with booleans, you should write only True or False , without the quotation marks.

In your case, as you're reading a value from the input() , it is much easier to just leave it as a string and compare it with "True" and "False" instead. So you could do as follow:

ans_male = input("Are you a male? (True or False): ")
if ans_male == "True": # Check if string is equal to "True"
    is_male.append(True) # Appends the boolean value True to the list.

Answer 2

Here ans_male will have true value even if your input is false. You can't convert string to bool value like this. Better create a function to convert string into bool values as following.

def stringToBool(ans_male):
    if ans_male == 'True':
       return True
    else if ans_male == 'False'
       return False
    else:
       raise ValueError

Answer 3

Booleans don't have quotation marks, those are only for strings. The following is 1/4 of your code with this change applied:

    is_male = []

    ans_male = bool(input("Are you a male? (True or False): "))
    if ans_male == "True":
        is_male.append(True)
    if ans_male == "False":
        is_male.append(False)

Note: ans_male == "True" has the boolean in string format because values assigned using input() are always strings.

Because of this , you may want to use the following instead (because follow):

is_male = []
    is_female = []
    is_tall = []
    is_short = []

    ans_male = bool(input("Are you a male? (Yes or No): "))
    if ans_male == "Yes":
        is_male.append(True)
    if ans_male == "No":
        is_male.append(False)
    ans_female = bool(input("Are you a male? (Yes or No): "))
    if ans_female == "Yes":
        is_female.append(True)
    if ans_female == "No":
        is_female.append(False)
    ans_tall = bool(input("Are you a male? (Yes or No): "))
    if ans_tall == "Yes":
        is_tall.append(True)
    if ans_tall == "No":
        is_tall.append(False)
    ans_short = bool(input("Are you a male? (Yes or No): "))
    if ans_short == "Yes":
        is_short.append(True)
    if ans_short == "No":
        is_short.append(False)

Answer 4

is_male.append(True) should work. I tested it and it works for me on v3.7.4.

Answer 5

Consider this code. You have a list of questions you want to ask, paired with the associated property (is_male, etc.). You have a dictionary that maps user input to a boolean. For each question, you print the current question and wait for the user to enter something. If they enter something invalid (something other than "True" or "False"), the while-loop will keep asking the same question until the user answers satisfactorily. When the user has answered all questions we print the results.

questions = [
    ("Are you male?", "is_male"),
    ("Are you tall?", "is_tall")
]

input_to_bool = {
    "True": True,
    "False": False
}

user = {}

for question, key in questions:
    while True:
        user_input = input(f"{question}: ")
        if user_input in input_to_bool:
            user.update({key: input_to_bool[user_input]})
            break

for key, value in user.items():
    print(f"{key}: {value}")

Output:

Are you male?: True
Are you tall?: False
is_male: True
is_tall: False

Answer 6

Your code transform the user input to bool.

ans_male = bool(input("Are you a male? (True or False): "))

So any input will be True and no input will be False.

How about doing something like:

is_male = []
ans_male = input('Are you a male? (Y or N): ')

if ans_male.upper() == 'Y':
    is_male.append(True)

elif ans_male.upper() == 'N':
    is_male.append(False)

else:
    print('Please choose Y or N')
    pass

Answer 7

Put your less affords and time with this code :

    is_male = []
    is_female = []
    is_tall = []
    is_short = []

    que = "Are you {} (Yes/No) : "

    ans_male = True if input(que.format("a male?")).lower()=='yes' else False
    is_male.append(str(ans_male))
    #if you want to append list with 'True'/'False' (type->str)

    ans_female = True if input(que.format("a female?")).lower()=='yes' else False
    is_female.append(ans_female)
    #if you want to append list with True/False (type -> bool)

    ans_tall = True if input(que.format("tall?")).lower()=='yes' else False
    is_tall.append(ans_tall)

    ans_short = True if input(que.format("short?")).lower()=='yes' else False
    is_short.append(ans_short)

It is the same code that you post in the question with efficient solution.

And yes an answer should be Yes/No because True/False sometime looks weird for this type of questions.