Cannot Use Float in BMI Calculator-CodePudding

I've built the following code:

# 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)

For whatever reason, when I input "75" for the weight value and "1.7" for the height value, it simply returns:

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

Process finished with exit code 0

If I use integers, it works fine:

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

Process finished with exit code 0

I need to be able to have my users input a string and then convert it to a float afterwards. What am I doing wrong here? I appreciate the help!

CodePudding user response：

Try to avoid integer division at the bmivalue calculation

bmivalue =  weight / (height ** 2)

instead of

bmivalue = weight // (height ** 2)

And make sure to correct the statement at

elif bmivalue <= 25.0 and bmivalue >= 29.9:

change to

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

CodePudding user response：

well, there's is an issue in your second elif you should change that to >=25 and <=29.9:

and also try using parenthesis it makes life easier to debug

# 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)

CodePudding user response：

Your code contains unnecessary and repeated comparisons. It also doesn't contain any kind of validation. Try this (output modified):

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))

Example:

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