import jsonfile = 'favnum.json'def save_fav(): number = input('Type your favourite number: ') with open(file, 'w') as f: num = json.dump(number, f) return numdef get_stored_number(): try: with open(file) as f: number_fav = json.load(f) except FileNotFoundError: return None else: return number_favdef main_number(): num = get_stored_number() if num: print('your favourite number is: ') print(num) else: print('the number had not saved before\nthus you have to save it') numbers = save_fav() print('your number is saved') print(numbers)main_number()輸出：the number had not saved beforethus you have to save itType your favourite number: 3.14your number is savedNone
3 回答
largeQ
TA貢獻2039條經驗 獲得超8個贊
我認為你的功能：
def save_fav():
number = input('Type your favourite number: ')
with open(file, 'w') as f:
num = json.dump(number, f)
return num
應該是這樣的：
def save_fav():
number = input('Type your favourite number: ')
with open(file, 'w') as f:
json.dump(number, f)
return number
在您的版本中，json.dump返回None，這就是您從函數返回的內容，然后稍后打印。
慕田峪4524236
TA貢獻1875條經驗 獲得超5個贊
因為json.dump除了 None 之外不會返回任何內容，并且您將其保存在 num 中，并返回 num 所以函數也返回 num 。因此，返回任何有意義的其他內容，例如空字符串。
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