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I am trying to learn tkinter. I have written a code to add two numbers and show the result below. But I get an error. Anybody can let me know where I have a mistake? Thank you

This is my code:

from tkinter import *

root = Tk()
root.geometry("400x400")

label1 = Label(root, text="your first number:").grid(row=0, column=0)
label2 = Label(root, text="your second number:").grid(row=1, column=0)

first_no  = IntVar()
second_no = IntVar()

entry1 = Entry(root, textvariable = first_no).grid(row=0, column=1)
entry2 = Entry(root, textvariable = second_no).grid(row=1, column=1)

def add():
    sumation = first_no.get() + second_no.get()
    label3.config(text = "your final number is:" + str(sumation))
    
mybutton = Button(root, text="Calculate!", command = add).grid(row=2, column=1)

label3 = Label(root).grid(row=3, column=1)

root.mainloop()

and this is the error:

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\pymnb\anaconda3\lib\tkinter\__init__.py", line 1892, in __call__
    return self.func(*args)
  File "<ipython-input-13-6c227c88abbc>", line 17, in addition
    label3.config(text = "your final number is:" + str(sumation))
AttributeError: 'NoneType' object has no attribute 'config'
pymn
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  • Within ```add()```, ```label3``` isn't defined. Try moving the ```label3 = ...``` before the ```add()``` function. – ewokx Feb 06 '22 at 23:57
  • Thanks for your reply. I saw similar videos on youtube, and it was working after the function. I moved that before function, but it gives the same error. – pymn Feb 07 '22 at 00:03
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    Does this answer your question? [Tkinter: AttributeError: NoneType object has no attribute ](https://stackoverflow.com/questions/1101750/tkinter-attributeerror-nonetype-object-has-no-attribute-attribute-name) – jasonharper Feb 07 '22 at 00:10
  • thanks for your reply. @eenNaampje resolved that below. the problem is because of the grid(). It should be written in two lines. thanks – pymn Feb 07 '22 at 00:15

2 Answers2

2

It errors bc .grid doesnt return the label. so do it two steps

from tkinter import *

root = Tk()
root.geometry("400x400")

Label(root, text="your first number:").grid(row=0, column=0)
Label(root, text="your second number:").grid(row=1, column=0)
# define the label, step 1
label3 = Label(root)
# set grid, step 2
label3.grid(row=3, column=1)

first_no = IntVar()
second_no = IntVar()

# same goes for here
entry1 = Entry(root, textvariable=first_no).grid(row=0, column=1)
entry2 = Entry(root, textvariable=second_no).grid(row=1, column=1)


def add():
    sumation = first_no.get() + second_no.get()
    label3.config(text="your final number is:" + str(sumation))

# and here
mybutton = Button(root, text=("Calculate!"), command=add).grid(row=2, column=1)

root.mainloop()
eenNaampje
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0

You forget to instance label3:

label3 = Label(root, text="result:").grid(row=3, column=0)

Because of that this line is returning "NoneType"

label3.config(text="your final number is:" + str(sumation))
Jean Jacques Barros
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