不能在 BMI 計算器中使用浮點數

Question

我構建了以下代碼：

# function to calculate bmi and return a result based on user input

def calculatebmi(weight, height):
    bmivalue = weight // (height ** 2)
    if bmivalue < 18.5:
        print("Underweight "), print(bmivalue)
    elif bmivalue >= 18.5 and bmivalue <= 24.9:
        print("Healthy "), print(bmivalue)
    elif bmivalue <= 25.0 and bmivalue >= 29.9:
        print("Overweight "), print(bmivalue)
    elif bmivalue >= 30.0:
        print("Obese "), print(bmivalue)


# establish usable variables based on user input

user_weight_kg1, user_height_m1 = input("What is your weight in kilograms? "), input("What is your height in meters? ")

# convert user input to float

user_weight_kg2, user_height_m2 = float(user_weight_kg1), float(user_height_m1)

# run the function

calculatebmi(user_weight_kg2, user_height_m2)

無論出於何種原因，當我輸入“75”作為重量值和“1.7”作為高度值時，它只會返回：

What is your weight in kilograms? 75
What is your height in meters? 1.7

Process finished with exit code 0

如果我使用整數，它工作正常：

What is your weight in kilograms? 80
What is your height in meters? 2
Healthy 
20.0

Process finished with exit code 0

我需要能夠讓我的用戶輸入一個字符串，然后將其轉換為浮點數。 我在這里做錯了什么？ 感謝您的幫助！

Answer 1

盡量避免在bmivalue計算時進行整數除法

bmivalue =  weight / (height ** 2) 

代替

bmivalue = weight // (height ** 2)

並確保在以下位置更正聲明

elif bmivalue <= 25.0 and bmivalue >= 29.9:

改成

elif (bmivalue >= 25.0) and (bmivalue <= 29.9):

Answer 2

好吧，您的第二個 elif 存在問題，您應該將其更改為 >=25 和 <=29.9：

• 並嘗試使用括號它使調試更容易

# function to calculate bmi and return a result based on user input
def calculatebmi(weight, height):
    bmivalue = weight // (height ** 2)
    if bmivalue < 18.5:
        print("Underweight "), print(bmivalue)
    elif (bmivalue >= 18.5) and (bmivalue <= 24.9):
        print("Healthy "), print(bmivalue)
    elif (bmivalue <= 29.9) and (bmivalue >= 25.0):
        print("Overweight "), print(bmivalue)
    elif bmivalue >= 30.0:
        print("Obese "), print(bmivalue)


# establish usable variables based on user input
user_weight_kg1, user_height_m1 = input(
    "What is your weight in kilograms? "), input("What is your height in meters? ")
# convert user input to float
user_weight_kg2, user_height_m2 = float(user_weight_kg1), float(user_height_m1)
# run the function
calculatebmi(user_weight_kg2, user_height_m2)

Answer 3

您的代碼包含不必要的重復比較。 它也不包含任何類型的驗證。 試試這個（輸出修改）：

def get_bmi(weight, height):
    try:
        if (BMI := float(weight) / (float(height) ** 2)) < 18.5:
            c = 'Underweight'
        elif BMI < 25.0:
            c = 'Healthy'
        elif BMI < 30.0:
            c = 'Overweight'
        else:
            c = 'Obese'
        return f'{BMI=:.1f} -> {c}'
    except ValueError as e:
        return str(e)

weight = input('Input weight in kg: ')
height = input('Input your height in metres: ')

print(get_bmi(weight, height))

例子：

Input weight in kg: 72
Input height in metres: 1.8
BMI=22.2 -> Healthy