グローバル変数を使わずに関数の中の変数を変更する方法

足し算の問題を出してその正解数を求める関数を作ろうとしています。下記のコードではcheckAnswer()がループ毎に0で初期化しているので正解数がカウントされていないと思うのですが、グローバル変数を使わずに関数の中の変数をカウントするにはどうしたらいいでしょうか？試しにproblem()の下に書いてもUnboundLocalErrorが出てダメでした。

python
1import random
2def problem():
3    for i in range(1, 4):
4        first_num = random.randint(1, 20)
5        second_num = random.randint(1, 20)
6        print(first_num, "+", second_num, "= ", end="")
7        user_num = int(input())
8        def calculateCorrectAnswer():
9            answer = first_num + second_num
10            return answer
11        def checkAnswer(correct_answer):
12            counter_correct = 0
13            if (user_num == correct_answer):
14                print("correct")
15                counter_correct += 1
16            else:
17                print("incorrect")
18            return counter_correct
19        
20        correct_answer = calculateCorrectAnswer()
21        user_correct = checkAnswer(correct_answer)
22    return user_correct
23
24A = problem()
25print("正解数は", A, "です")
26
27"""
28(output)
292 + 3 = 5
30correct
317 + 4 = 11
32correct
339 + 7 = 16
34correct
35正解数は 1 です
36"""
37

y_waiwai

2021/07/12 14:11

あなたの言ってる変数とはどれのことでしょうか

erumoa400

2021/07/13 05:32

checkAnswer()の中のcounter_correctのことです。分かりにくくてすみません

行動規範の内容に同意します

回答3件

ベストアンサー

こういうときのために、nolocal変数があります。

7.13. nonlocal 文

これを使うと、以下のように書けます。

python
1import random
2
3def problem():
4    counter_correct = 0
5    for i in range(1, 4):
6        first_num = random.randint(1, 20)
7        second_num = random.randint(1, 20)
8        print(first_num, "+", second_num, "= ", end="")
9        user_num = int(input())
10        def calculateCorrectAnswer():
11            answer = first_num + second_num
12            return answer
13        def checkAnswer(correct_answer):
14            nonlocal counter_correct
15            if (user_num == correct_answer):
16                print("correct")
17                counter_correct += 1
18            else:
19                print("incorrect")
20        correct_answer = calculateCorrectAnswer()
21        checkAnswer(correct_answer)
22    return counter_correct

投稿2021/07/12 14:35

ppaul

総合スコア24670

erumoa400

2021/07/13 05:34

nonlocal変数なんてあるですね...勉強になりますおかげで無事解決しました。回答ありがとうございます

行動規範の内容に同意します

counter_correct をリストにして、その要素を +1 するという手もあります。

Python
1import random
2def problem():
3	counter_correct = [ 0 ]
4	for i in range(1, 4):
5		first_num = random.randint(1, 20)
6		second_num = random.randint(1, 20)
7		print(first_num, "+", second_num, "= ", end="")
8		user_num = int(input())
9		def calculateCorrectAnswer():
10			answer = first_num + second_num
11			return answer
12		def checkAnswer(correct_answer):
13			if (user_num == correct_answer):
14				print("correct")
15				counter_correct[0] += 1
16			else:
17				print("incorrect")
18			return counter_correct[0]
19
20		correct_answer = calculateCorrectAnswer()
21		user_correct = checkAnswer(correct_answer)
22	return user_correct
23
24A = problem()
25print("正解数は", A, "です")
26

でも、この場合、checkAnswer が値を返す必要はなく、user_correct も不要になります。

Python
1import random
2def problem():
3	counter_correct = [ 0 ]
4	for i in range(1, 4):
5		first_num = random.randint(1, 20)
6		second_num = random.randint(1, 20)
7		print(first_num, "+", second_num, "= ", end="")
8		user_num = int(input())
9		def calculateCorrectAnswer():
10			answer = first_num + second_num
11			return answer
12		def checkAnswer(correct_answer):
13			if (user_num == correct_answer):
14				print("correct")
15				counter_correct[0] += 1
16			else:
17				print("incorrect")
18
19		correct_answer = calculateCorrectAnswer()
20		checkAnswer(correct_answer)
21	return counter_correct[0]
22
23A = problem()
24print("正解数は", A, "です")

投稿2021/07/13 00:17

kazuma-s

総合スコア8224

erumoa400

2021/07/13 05:41

リストをこんなふうに使えるのは知りませんでした...回答ありがとうございます

行動規範の内容に同意します

python
1import random
2
3def problem():
4    user_correct = 0
5    for i in range(1, 4):
6        first_num = random.randint(1, 20)
7        second_num = random.randint(1, 20)
8        print(first_num, "+", second_num, "= ", end="")
9        user_num = int(input())
10        
11        def calculateCorrectAnswer():
12            answer = first_num + second_num
13            return answer
14        
15        def checkAnswer(correct_answer):
16            counter_correct = 0
17            if (user_num == correct_answer):
18                print("correct")
19                counter_correct += 1
20            else:
21                print("incorrect")
22            return counter_correct
23
24        correct_answer = calculateCorrectAnswer()
25        user_correct += checkAnswer(correct_answer)
26        
27    return user_correct
28
29A = problem()
30print("正解数は", A, "です")