python - Why does my Tkinter calculator only output 0?

Question

I have been trying to make a simple calculator in python using the Tkinter module, and all it does is display 0. Here is the code:

import tkinter as tk
window = tk.Tk()
calclabel = tk.Label(text = "This is a calculator.
Type yor numbers in the space given below and click on any on the operators to carry out the operation.")
calclabel.pack()
entry1 = tk.Entry()
entry1.pack()
entry2 = tk.Entry()
entry2.pack()
a = int()
b = int()
entry1.get = a
entry2.get = b
def addcommand () :
    addlabel = tk.Label(text = a+b)
    addlabel.pack()

def subcommand () :
    sublabel = tk.Label(text = a-b)
    sublabel.pack()

def multicommand () :
    multilabel = tk.Label(text = a*b)
    multilabel.pack()

def divicommand () :
    divilabel = tk.Label(text = a/b)
    divilabel.pack()

add = tk.Button(text = "Add",
                command = addcommand,
                master = window)
add.pack()

sub = tk.Button(text = "Substract",
                command = subcommand,
                master = window)
sub.pack()

mul = tk.Button(text = "Multiply",
                command = multicommand,
                master = window)
mul.pack()

div = tk.Button(text = "Divide",
                command = divicommand,
                master = window)
div.pack()

Any help would be greatly appreciated, because I think it is a logic error and I cannot figure it out.

question from:https://stackoverflow.com/questions/65885820/why-does-my-tkinter-calculator-only-output-0

Answer 1

It seems you are doing it the wrong way. Every time you perform any command, you should get the value from entry and then calculate. Like shown below

def addcommand () :
    a = int(entry1.get()) # get the value from entry1 and cast it to integer
    b = int(entry2.get()) # get the value from entry1 and cast it to integer
    addlabel = tk.Label(text = a+b) # do the calculation
    addlabel.pack()

You can use try except block during casting for handling exception.

Here is how you can do it

import tkinter as tk
window = tk.Tk()
calclabel = tk.Label(text = "This is a calculator.
Type yor numbers in the space given below and click on any on the operators to carry out the operation.")
calclabel.pack()
entry1 = tk.Entry()
entry1.pack()
entry2 = tk.Entry()
entry2.pack()
# a = int()
# b = int()
# entry1.get = a
# entry2.get = b
def addcommand () :
    a = int(entry1.get())
    b = int(entry2.get())
    addlabel = tk.Label(text = a+b)
    addlabel.pack()

def subcommand () :
    a = int(entry1.get())
    b = int(entry2.get())
    sublabel = tk.Label(text = a-b)
    sublabel.pack()

def multicommand () :
    a = int(entry1.get())
    b = int(entry2.get())
    multilabel = tk.Label(text = a*b)
    multilabel.pack()

def divicommand () :
    a = int(entry1.get())
    b = int(entry2.get())
    divilabel = tk.Label(text = a/b)
    divilabel.pack()

add = tk.Button(text = "Add",
                command = addcommand,
                master = window)
add.pack()

sub = tk.Button(text = "Substract",
                command = subcommand,
                master = window)
sub.pack()

mul = tk.Button(text = "Multiply",
                command = multicommand,
                master = window)
mul.pack()

div = tk.Button(text = "Divide",
                command = divicommand,
                master = window)
div.pack()

tk.mainloop()