Python Tkinter Quiz score system -

i making quiz in python (using tkinter). stuck on score system have made variable called 'score' when try add + 1 score gets error. have tried define before procedure still doesn't work.

import tkinter tk window = tk.tk() window.title("6 questions") window.geometry("500x150") def inst():     t = tk.label(window, text="all need answer each question either '1, 2, 3' or actual word.")     t.pack() def start():     score = 0     q1 = tk.tk()     q1.title("question 1")     q = tk.label(q1, text="what type of input holds whole numbers?")     q.pack()     = tk.label(q1, text="1.) int")     a.pack()     b = tk.label(q1, text="2.) string")     b.pack()     c = tk.label(q1, text="3.) float")     c.pack()     ans = tk.entry(q1, width=40)     ans.pack()     def qu1():         deranswer = ans.get()         if deranswer == "1" or deranswer == "int":             crr = tk.label(q1, text="correct!", fg="green")             crr.pack()             score = score + 1             q2 = tk.tk()             q2.title("question 2")             qw = tk.label(q2, text="choose correct code:")             qw.pack()             ans21 = tk.label(q2, text="1.) print hello world")             ans21.pack()             ans32 = tk.label(q2, text="2.) print hello world()")             ans32.pack()             ans43 = tk.label(q2, text="3.) print('hello world')")             ans43.pack()             ans2 = tk.entry(q2, width=40)             ans2.pack()             def qu2():                 deranswer = ans2.get()                 if deranswer == "3" or deranswer == "print('hello world')":                     crr = tk.label(q2, text="correct!", fg="green")                     crr.pack()                     score = score + 1                     q3 = tk.tk()                     q3.title("question 3")                     qu3 = tk.label(q3, text="what variable?")                     qu3.pack()                     ans56 = tk.label(q3, text="1.) stores food")                     ans56.pack()                     ans65 = tk.label(q3, text="2.) name stores piece of data")                     ans65.pack()                     ans45 = tk.label(q3, text="3.) displays word")                     ans45.pack()                     ans25 = tk.entry(q3, width=40)                     ans25.pack()                     def qu2():                         deranswer = ans25.get()                         if deranswer == "2" or deranswer == "a name stores piece of data":                             crr = tk.label(q3, text="correct!", fg="green")                             crr.pack()                             score = score + 1                             dis = tk.label(q3, text=score, fg="blue")                         else:                             incr = tk.label(q3, text="incorrect!", fg="red")                             incr.pack()                     sub = tk.button(q3, text="submit", command=qu2)                     sub.pack()                 else:                     incr = tk.label(q2, text="incorrect!", fg="red")                     incr.pack()             sub = tk.button(q2, text="submit", command=qu2)             sub.pack()         else:             incr = tk.label(q1, text="incorrect!", fg="red")             incr.pack()     sub = tk.button(q1, text="submit", command=qu1)     sub.pack()   greet = tk.label(window, text="welcome 6 question quiz.") greet.pack() start = tk.button(window, command=start, text="start") start.pack() instr = tk.button(window, text="instructions", command=inst) instr.pack() end = tk.button(window, text="exit", command=exit) end.pack() 

from comment traceback:

line 27, in qu1 score = score + 1 unboundlocalerror: local variable 'score' referenced before assignment

you trying add score , +1 itself, score not defined within function. variables have scope. read more in the python documentation.