Python - TypeError：“NoneType”对象不可迭代

Posted 2023-02-23

【中文标题】Python - TypeError：“NoneType”对象不可迭代

【英文标题】：Python - TypeError: 'NoneType' object is not iterable

【发布时间】：2017-08-29 01:58:38

【问题描述】：

我试图阻止输入除整数以外的任何平均值作为平均值，但我不断收到 TypeError 的 Traceback。下面是我的程序，以及尝试输入除 int 以外的任何内容作为平均值时的程序输出：

grades_file = open('grades.txt', 'w')

def get_averages():
    student = 1
    for i in range(3):
        name, average = get_name_average()
        student += 1
        grades_file = open('grades.txt', 'a')
        grades_file.write("Student Name: " + name + '\n' + "Student Average: " + str(average) + '\n\n')
        grades_file.close()
        print(("Added %s's average of %i to the file 'grades.txt. You are now entering information for student %i of 12.") % (name, average, student))
def get_name_average():
    student_name = input("Please enter the student's name: ")
    try:
        student_average = int(input(("Please enter the average for %s: ") % student_name))
        verified_average = check_grade_input(student_average)
        return student_name, verified_average
    except ValueError:
        print("ERROR!! Please enter grade value as an integer!")
    except TypeError:
        print('Type error too!')

def check_grade_input(average):
    legal_input = False
    while not legal_input:
        if (average < 0):
            print("Nah bro,  invalid number...")
            average = int(input("Please enter another average that is above 0: "))
        elif (average > 100):
            print("Nah bro,  invalid number...")
            average = int(input("Please enter another average that is below 100: "))
        else:
            return average

def show_grades_file():
    grades_file = open('grades.txt', 'r')
    grade_contents = grades_file.read()
    grades_file.close()
    print("\nThe information you entered for into file 'grades.txt' is:\n\n" + grade_contents)

def main():
    get_averages()
    show_grades_file()

main()

回溯和输入：

Please enter the student's name: Aaron
Please enter the average for Aaron: as
ERROR!! Please enter grade value as an integer!
Traceback (most recent call last):
  File "Documents/ProgrammingFundamentals/Lab6/aaron_blakey_Lab6b.py", line 52, in <module>
    main()
  File "Documents/ProgrammingFundamentals/Lab6/aaron_blakey_Lab6b.py", line 49, in main
    get_averages()
  File "Documents/ProgrammingFundamentals/Lab6/aaron_blakey_Lab6b.py", line 13, in get_averages
    name, average = get_name_average()
TypeError: 'NoneType' object is not iterable

【参考方案1】：

在函数 get_name_average 中，您在异常部分打印了消息 print("ERROR!! Please enter grade value as an integer!")，但您没有返回任何值.

默认情况下，系统将返回无值和必需的两个值名称、平均值。

您需要遵循以下代码。

def get_name_average():
    student_name = input("Please enter the student's name: ")
    try:
        student_average = int(input(("Please enter the average for %s: ") % student_name))
        verified_average = check_grade_input(student_average)
        return student_name, verified_average
    except ValueError:
        print("ERROR!! Please enter grade value as an integer!")
        return False,False
    except TypeError:
        print('Type error too!')
        return False,False

之后，如果您遇到异常，则 name,average=False,False。

在get_averages函数中，如果名称为False，则需要添加一个条件，则系统不应写入文件。

这可能会对你有所帮助。