在Python中將非類型和整數相乘和除

Question

所以我正在寫一個計算你的BMI的簡單程序。 當我需要通過獲取重量和高度的返回值來計算BMI時，我遇到了一個問題（就好像沒有返回值一樣）。 當我在一個函數中包含所有模塊時，此代碼用於工作，因為我已將所有函數划分為我遇到此問題的單獨模塊。

>     Error:
>     Traceback (most recent call last):
>       File "C:/OneDrive/Documents/3.py", line 43, in <module>
>         bmi = calcBMI(weight, height)
>       File "C:/OneDrive/Documents/3.py", line 17, in calcBMI
>         bmi = float(weight * 703 / (height * height))
>     TypeError: unsupported operand type(s) for *: 'NoneType' and 'int'

這是我的代碼：

 ########## # Functions ########## def getweight(): weight = float(input('Enter your weight in LBs: ')) if weight <= 0 or weight > 1000: print('Weight cannot be less than 0 or greater than 700') return weight def getheight(): height = float(input('Enter your height in inches: ')) if height <= 0: print('Height cannot be less than 0') return height def calcBMI(weight, height): bmi = float(weight * 703 / (height * height)) return bmi def printData(name, bmi): print(name) print('Your BMI is %.2f' % bmi) if bmi >= 18.5 and bmi <= 24.9: print('Your BMI is normal') elif bmi <= 18.5: print('Your BMI is underweight') elif bmi >= 25 and bmi <= 29.9: print('Your BMI is overweight') elif bmi >= 30: print('**Your BMI is obese**') ##################### # Beginning of program ##################### print("Welcome to the Body Mass Index Calculator") name = input('Enter your name or 0 to quit: ') # beginning of loop while name != "0": height = getheight() weight = getweight() bmi = calcBMI(weight, height) printData(name, weight, height, bmi) name = input('Enter another name or 0 to quit: ') print("Exiting program...") 

Answer 1

首先，如果它小於0，則只返回高度。您可能希望從if塊中刪除return語句。

您可能還想創建一些邏輯來處理輸入的錯誤高度，例如引發異常或將用戶返回到提示符。

def getweight():
    weight = float(input('Enter your weight in LBs: '))
    if weight <= 0 or weight > 1000:
        print('Weight cannot be less than 0 or greater than 700')
        #Some code here to deal with a weight less than 0
    return weight

def getheight():
    height = float(input('Enter your height in inches: '))
    if height <= 0:
        print('Height cannot be less than 0')
        #Some code here to deal with a height less than 0
    return height

處理不正確權重的一種方法是：

def getweight():
    while True:
        weight = float(input('Enter your weight in LBs: '))
        if weight <= 0 or weight > 1000:
            print('Weight cannot be less than 0 or greater than 700')
        else:
            return weight

您可能希望將此限制為一定數量的迭代 - 由您決定。

Answer 2

getheight和getweight都不一定會返回一個數字（即當if失敗時）; 在這種情況下，它返回None 。