What am I doing wrong with the variables?

Question

I wanted to make a little program to change the capitalization of sentences to make them sound very sarcastic. I wanted to have it in a little frame and used this tutorial ( https://datatofish.com/entry-box-tkinter/ ). I've extracted some of its code and implemented it, but I think I messed up.

The Shell constantly gives me errors about missing variable which I can't seem to find in the code. Can some of you find where I made the mistake?

import random
import tkinter as tk

root= tk.Tk()
root.title('hOofDleTteRdiNGes')

canvas1 = tk.Canvas(root, width = 400, height = 300)
canvas1.pack()

entry1 = tk.Entry (root)
canvas1.create_window(200, 140, window=entry1)

def capi_sentence(sentence):
    sentence.lower = entry1.get()
    new_sentence = ''
    number = 0 #Dummy number for tracking

    for letter in sentence.lower():
        if len(new_sentence)<2: #Creates the first two letter
            random_number = random.randint(0,1) #This randomly decides if the letter should be upper or lowercase
            if random_number==0:
                new_sentence += letter.upper()
            else:
                new_sentence += letter
        else:
            if (new_sentence[number-2].isupper() and new_sentence[number-1].isupper() or new_sentence[number-2].islower() and new_sentence[number-1].islower())==True:
                #Checks if the two letters before are both upper or lowercase
                if new_sentence[number-1].isupper(): #Makes the next letter the opposite of the letter before
                    new_sentence += letter.lower()
                else:
                    new_sentence += letter.upper()
            else:
                random_number = random.randint(0,1)
                if random_number==0:
                    new_sentence += letter.upper()
                else:
                    new_sentence += letter
                
        number += 1 #Add one more to the tracking
     
    label1 = tk.label(new_sentence)

button1 = tk.Button(text='hoofdletter shufflen', command=capi_sentence)
canvas1.create_window(200, 180, window=button1)

Answer 1

You have a few problems.

1. You need to call root.mainloop() at the end so a window will appear.

2. Your capi_sentence function takes an argument but the callback called when pressing the button does not give it one.

Use

button1 = tk.Button(text='hoofdletter shufflen', command=lambda: capi_sentence(entry1.get()))

which calls your function with the return value of entry1.get() .

3. The first line of capi_sentence is unnecessary (and doesn't really make sense anyway) after you properly pass in the text.

4. You've used lowercase label when creating the label. You also need to pass in a parent widget (eg root) and pass in the text as the text keyword argument. Finally, you need to add it to the window by packing it.

    label1 = tk.Label(root, text=new_sentence)
    label1.pack()

Some misc tips:

You do not need == True at the end of your conditional; if will already run if true.

You can remove the explicit number logic by using enumerate , which returns a list of tuples (i, item), with item the original item in the list and i its index from 0 to N - 1. I've rewritten your for loop below with this (and other simplifications) so it's a bit easier to read.

for i, letter in enumerate(sentence.lower()):
  maybe_upper = letter.upper() if random.randint(0, 1) else letter
  if len(new_sentence) < 2: #Creates the first two letter
    new_sentence += maybe_upper
  else:
    l2, l1 = new_sentence[i - 2 : i]
    if (l1.isupper() and l2.isupper()) or (l1.islower() and l2.islower()):
      #Checks if the two letters before are both upper or lowercase
      new_sentence += letter.lower() if l1.isupper() else letter.upper()
    else:
      new_sentence += maybe_upper