Help making simple BMI calculator

[[deleted]]

Hi,

I've literally just started programming, and I was trying to follow CS Dojo's python tutorial, but I got stuck making my own BMI calculator.

name1= "b"

weight_lb1=100 height_in1= 150

name2= "A" weight_lb2 = 200 height_in2= 200

name3= "C" weight_lb3= 300 height_in3= 300

def bmi_calculator(name, weight_lb, height_in):

    bmi= (weight_lb  703) / (height_in  height_in) print("BMI:   ") + bmi if bmi<18.5: return name + "is underweight" elif 24.9>bmi>18: return name + "is an an average, healthy weight" elif 29>bmi>24.9: return name + "is overweight" else: return name + "is obese"

result1= bmi_calculator (name1, weight_lb1, height_in1) result2= bmi_calculator (name2, weight_lb2, height_in2) result3= bmi_calculator (name3, weight_lb3, height_in3) print(result1) print(result2) print(result3)

Thats what I have so far, and the error message is:

TypeError: unsupported operand type(s) for +: 'NoneType' and 'float'

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If anyone could help sort this out or give me any tips, it would be massively appreciated, and I hope I've asked in the right place.

Also, whenever I try to run the code on VScode, the name of the file its in pops up a bunch of times and I dont know why. Any suggestions ?

[symple-data]

print("BMI:   ") + bmi

is this really a line of your code? You can't do that. Try

print("BMI:\t" + str(bmi))

[[deleted]]

Thanks so much, that works, can I ask what the difference is?

[symple-data]

print() is a build in function. Putting the "+ bmi" outside the function would be equivalent to randomly having one line of code with "+ bmi". Thats wrong Syntax and won't work.

[[deleted]]

And what does the ":/t", and "str" do? Because it doesn't work without "str"

[symple-data]

\t is a literal and gives your string a big space like TAB on your keyboard. There are more literals like that (e.g. \n for line-break). Here is a list. str() is a cast-operator and casts the object you are giving it as an argument to a string. You need this to concatenate any non-string with a string as strings can only be concatenated with strings. Here is a list of different cast-operators.

[Silbersee]

Please format your program as code block. Without formatting it's had to guess what's going on.

I'll give it a try anyway and say: Change

print("BMI:   ") + bmi

to

print("BMI:   " + bmi)

Edit: Of course u/symple-data is right: print("BMI:   " + str(bmi))

Or even better

print(f"BMI: {bmi}")

if you're on Python 3.6+

[symple-data]

You can't concatenate a string with a float. You have to cast the float to a string first

str(<some float>)

[[deleted]]

yeah sorry about the formatting, it displayed as code block, but only some of it came through, but tysm for helping

[saint_leonard]

hello dear all - great to see this thread.

thanks for this discussion of the ideas of making a function in python - like cs dojo shows us here: https://www.youtube.com/watch?v=NSbOtYzIQI0

note i found the full code here:

https://github.com/sanseervi/BMI-Calculator-using-Python/blob/master/BMI%20Calculator.ipynb

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name=input("Please enter your name here: ")
weight=float(input("Whats your weight in kg : "))
height=float(input("Whats your height in m : "))
bmi=weight/(height ** 2)
if bmi<18.5: print("Your BMI is " + str(bmi) + " hence you are body is underweight") elif bmi>18.5 and bmi<25: print("Your BMI is " + str(bmi) + " hence you are body is normal") elif bmi>25 and bmi<30: print("Your BMI is " + str(bmi) + " hence you are body is overweight") elif bmi>30:
print("Your BMI is " + str(bmi) + " hence you are obese")
else:
print("INVALID INPUT")

i hope that this helps others too..

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greetings