Note how the button's command calls the function to perform your operation:
from tkinter import *
def find_isbn(isbn, lbl):
if len(isbn) == 10:
mult = 11
total = 0
for i in range(len(isbn)):
total += int(isbn[i]) * mult
mult -= 1
digit_11 = 11 - (total % 11)
if digit_11 == 10:
digit_11 = 'X'
isbn += str(digit_11)
lbl.config(text=isbn)
top = Tk()
top.geometry("450x450+500+300")
top.title("Test")
button = Button(top, text="OK", command=lambda: find_isbn(mEntry.get(), mlabel2), fg="red", bg="blue")
button.pack()
label = Label(top, text="Please enter the 10 digit number")
label.pack()
mEntry = Entry(top)
mEntry.pack()
mlabel2 = Label(top, text='')
mlabel2.pack()
top.mainloop()
You also need to call .mainloop()
, on your master widget to get the whole things started. It's also better to call .pack()
on an object on a separate line. pack()
and grid()
return nothing so you won't be able to use other methods on the object once you do that.