variable not defined even though it exists

Question

this is a simple code i wrote for the flanker task:

import random

congruent = open('congruent.txt', 'r')
incongruent = open('incongruent.txt', 'r')

def createList(file):
    lst = []
    for row in file:
        lst.append(row.strip('\n'))
    return lst
    file.close()

lstCongruent = createList(congruent)
lstIncongruent = createList(incongruent)

nr_trials = 20

def middleString(txt):
    middle = txt[(len(txt)-1)//2]
    return middle
    
def checkCongruency(item):
    if item in lstCongruent:
        correctCongruentAnswers = 0
        correctCongruentAnswers += 1
        return correctCongruentAnswers
    elif item in lstIncongruent:
        correctIncongruentAnswers = 0
        correctIncongruentAnswers += 1
        return correctIncongruentAnswers
            

for i in range(nr_trials):
    rndItem = random.choice(lstCongruent + lstIncongruent)
    print(rndItem)
    answer = input('Please write your answer: ')
    if answer == 'STOP':
        exit()
    while answer != 'F' and answer != 'J':
        print('\33[91m Please type only F or J \33[0m')
        break
        
    if middleString(rndItem) == '<' and answer == 'F':
        print('Correct answer!')
        checkCongruency(rndItem)
    elif middleString(rndItem) == '>' and answer == 'J':
        print('Correct answer!')
        checkCongruency(rndItem)
    else:
        print('Incorrect answer')
 
       
print('Correct congruent answers: ', correctCongruentAnswers)
print('Correct incongruent answers: ', correctIncongruentAnswers)

but when i run it, i get:

File "main.py", line 68, in <module>
    print('Correct congruent answers: ', correctCongruentAnswers)
NameError: name 'correctCongruentAnswers' is not defined

is there any way to solve this without completely changing the code? i've tried different things, like defining the functions inside the for loop or some other stuff, but it won't work.

Answer 1

Variables inside the method won't exist in the main script. If you wish to use the correctCongruantAnswers from the checkCongruency function, you must create a new variable to receive this value when you run checkCongruency() .

if middleString(rndItem) == '<' and answer == 'F':
    print('Correct answer!')
    congruency_result = checkCongruency(rndItem)
elif middleString(rndItem) == '>' and answer == 'J':
    print('Correct answer!')
    congruency_result = checkCongruency(rndItem)
else:
    print('Incorrect answer')

Answer 2

Since variable inside functions can only be use within the function, you can declare them as being global variables, albeit this is not good practice.

def checkCongruency(item):
    global correctCongruentAnswers #here
    global correctIncongruentAnswers #and here
    if item in lstCongruent:
        correctCongruentAnswers = 0
        correctCongruentAnswers += 1
        return correctCongruentAnswers
    elif item in lstIncongruent:
        correctIncongruentAnswers = 0
        correctIncongruentAnswers += 1
        return correctIncongruentAnswers