Why does my function return the same value without performing the required operations on it?

Question

My function doesn't work, I'm trying to build a simple program whit GUI. it can convert any temperature from any scale to the Kelvin scale by take from user a number of temperature and key to tell the function witch temperature scale you enter, this's a keys you can use it C or c == Celsius, K or k == kelvin, F or f == Fahrenheit and return [the key is unavailable] if the isn't one of them. But when I enter any key of these keys it's return the same value that I given it.

this is my code:

from tkinter import *
from tkinter import ttk
from turtle import width, window_width
from Science import Kelvin

window = Tk()

window.title('Chemical Physics')
window.geometry("300x200+10+20")

GetButton = ttk.Button(window, text = "--> Click here <--")
GetButton.pack()

EntryKelvinNumber = ttk.Entry(window, width = 40)
EntryKelvinNumber.pack()

EntryKelvinKey = ttk.Entry(window, width = 20)
EntryKelvinKey.pack()

def GetKelvinButton():
# the Kelvin function just return the same value 
    print(Kelvin(EntryKelvinNumber.get(),EntryKelvinKey.get()))
    
      
GetButton.config(command = GetKelvinButton)

window.mainloop()

this line from Science import Kelvin is import kelvin function from my own library.

this is a Kelvin function code:

def helpS():
    print("pleas use:\n")
    print("use 0 if your temperature is Kelvin\n")
    print("use 1 if your temperature is Celsius\n")
    print("use 2 if your temperature is Fahrenheit\n")
    #soon...

def Kelvin(Tempereture,key):
    if key == 'K' or 'k':
        return Tempereture
    elif key == 'C' or 'c':
        return Tempereture + 273.15
    elif key == 'F' or 'f':
        i = (Tempereture - 32)/1.8
        i = i + 273.15
        return i
    else:
        print("the key is unavailable")
        helpS()

I'm tryed to make the keys a numbers like 0 == Kelvin, 1 == Celsius, and 2 == Fahrenheit, But it still don't work.

This would appear to be a problem with the `Kelvin()` function, which you didn't show us. Perhaps it doesn't like being passed a temperature as a string rather than a number? — jasonharper, Sep 24 '22 at 15:26
Does this answer your question? [Why does "a == x or y or z" always evaluate to True? How can I compare "a" to all of those?](https://stackoverflow.com/questions/20002503/why-does-a-x-or-y-or-z-always-evaluate-to-true-how-can-i-compare-a-to-al) — jasonharper, Sep 24 '22 at 20:00

score 1 · Answer 1 · answered Sep 24 '22 at 18:59

if key == 'K' or 'k':

is equivalent to

if (key == 'K') or ('k'):

which is equivalent to

if True:

since bool('k') is True.

You probably wanted to write

if key == 'K' or key == 'K':

Also, make sure Temperature variable is a number in your function Kelvin as EntryKelvinNumber.get() will return a string.

def Kelvin(Tempereture, key):
    Tempereture = float(Tempereture)
    # rest of Kelvin function

Michal Borwoski · Accepted Answer · 2022-09-24T19:08:46.773

This is just a problem with the syntax of Python, You will have to use the code below. You have to use the same conditional statement after 'or', just with a different value, if you are making that condition.

def Kelvin(Tempereture,key):
    if key == 'K' or key == 'k':
        return Tempereture
    elif key == 'C' or key == 'c':
        return Tempereture + 273.15
    elif key == 'F' or key == 'f':
        i = (Tempereture - 32)/1.8
        i = i + 273.15
        return I
    else:
        print("the key is unavailable")
        helpS()

print(Kelvin(50, "c"))

Hope this works.

Why does my function return the same value without performing the required operations on it?

2 Answers2