Question

我正在尝试编写此代码，并且当我第一次运行该代码时，该函数有效，并且我能够将所有变量更新为列表并将该列表附加到course_catalogue。虽然，当我第二次运行函数时，出现了一个错误消息

UnboundLocalError：分配前已引用本地变量“可用性”。

有人知道为什么会这样吗？我该如何解决？

我程序的这个特定模块旨在向课程目录中添加一个包含所有信息（courseID，教师姓名等）的新课程，最终看起来像一个列表列表，每个特定课程都是一个列表在课程目录的更大列表中。

course_catalogue = []

def newcourse():
    course_code = input('What is the course code? ')
    department = input('Which department is this course in? ')
    instructor = input("What is the instructor's name? " )
    max_enrollment = input('What is the maximum enrollment for this course? ')
    current_enrollment = input('How many students are currently enrolled in this course? ')
    if max_enrollment > current_enrollment:
        availability = 'Available'
    if max_enrollment == current_enrollment:
        availability = 'Full'
    course_ID = [course_code, department, instructor, max_enrollment, current_enrollment, availability]
    course_catalogue.append(course_ID)

Answer 1

如果max_enrollment < current_enrollment，您没有任何条件的限制，因此在这种情况下，可用性将不存在。

另一个问题是max_enrollment和current_enrollment都是字符串，而不是整数。

max_enrollment = int(input('What is the maximum enrollment for this course? '))
current_enrollment = int(input('How many students are currently enrolled in this course? '))
if max_enrollment > current_enrollment:
    availability = 'Available'
elif max_enrollment == current_enrollment:
    availability = 'Full'
elif max_enrollment < current_enrollment:
    availability = 'Overfilled' # you can use whatever term you want here, or just swap the '==' for '<=' in the previous statement

Answer 2

之所以发生这种情况，是因为您的if条件并不详尽。在您的代码中：

if max_enrollment > current_enrollment:
    availability = 'Available'
if max_enrollment == current_enrollment:
    availability = 'Full'

但是如果max_enrollment < current_enrollment

我建议将零件更改为：

if max_enrollment > current_enrollment:
    availability = 'Available'
elif max_enrollment == current_enrollment:
    availability = 'Full'
else:
    availability = 'Something else'

Answer 3

发生错误的原因是，如果条件为availability，则变量if max_enrollment < current_enrollment:将不存在

更改条件：

if max_enrollment > current_enrollment:
    availability = 'Available'
if max_enrollment == current_enrollment:
    availability = 'Full'

为

if max_enrollment > current_enrollment:
    availability = 'Available'
else:
    availability = 'Full'

我一直在我的代码中遇到错误

3 个答案: