[FIXED] Program unresponsive on clicking a button in Tkinter?

Issue

I'm trying to create a simple calculator using Tkinter, but I'm facing a problem. First see the relevant code:

entry_text = StringVar()
inout = Entry(root, textvariable=entry_text)
inout.grid(row=0, column=0, columnspan=4, sticky="nsew")

def equals():
    print("Equal button is clicked")
    get_answer = True

def divide():
    tempvar = entry_text.get()
    num1 = int(tempvar)
    entry_text.set("")
    while get_answer == False:
        tempvar2 = entry_text.get()
        try:
            num2 = int(tempvar2)
        except ValueError:
            num2 = 0
    print("I'm out of the loop.")
    answer = num1 / num2
    entry_text.set(answer)

Here I'm creating a function for the divide button. The functionality of the button is whenever you click on the button, it takes the instantaneous value of the entry_text variable, stores it in a temporary variable and resets the value of entry_text variable. Then it runs a loop for collecting the next value of entry_text until the equal button is clicked. But the problem lies just here. Whenever I click on divide button, the GUI becomes unresponsive, and I don't get to enter the next value for the divide operation and get out of the loop.

Can anyone help?

Solution

Avoid using while loop in a tkinter application because it will block tkinter mainloop from handling pending events.

Also, get_answer inside equals() is a local variable because you haven't declare it as a global using global get_answer.

Actually you should perform the required operation inside equals(), but you need to store the first number and selected operation as global variables:

num1 = 0
operator = None

def equals():
    global num1, operator
    print("Equal button is clicked")
    try:
        tempvar = entry_text.get()
        num2 = float(tempvar)  # used float() instead of int()
        if operator == '/' and num2 != 0:
            answer = num1 / num2
            entry_text.set(answer)
            operator = None # reset operator
    except ValueError:
        print('Invalid value', tempvar)

def divide():
    global num1, operator
    try:
        tempvar = entry_text.get()
        num1 = float(tempvar)  # used float() instead of int()
        entry_text.set("")
        operator = '/'   # save the operator
    except ValueError:
        print('Invalid value', tempvar)

Answered By - acw1668