Python:从函数返回数组值

Question

我正在尝试了解如何正确使用函数。在此代码中，我想为学生姓名和百分比分数返回 2 个数组。但是我无法从第一个函数返回数组变量。

我尝试过使用不同的方式来定义数组(有和没有括号，全局和本地)

这是程序的相关代码部分

#function to ask user to input name and score
def GetInput():
    for counter in range(0,10):
        names[counter] = input("Please enter the student's name: ")
        
        valid = False
        while valid == False:
            percentages[counter] = int(input("Please enter the student's score %: "))
            if percentages[counter] < 0 or percentages[counter] > 100:
                print("Please enter a valid % [0-100]")
            else:
                valid = True
        return names, percentages

name, mark = GetInput()

我期待被要求输入两个数组的值。

我得到的是:

Traceback (most recent call last):
  File "H:/py/H/marks.py", line 35, in <module>
    name, mark = GetInput()
  File "H:/py/H/marks.py", line 7, in GetInput
    names[counter] = input("Please enter the student's name: ")
NameError: global name 'names' is not defined

Answer 1

如果你想使用键值对，你需要使用字典而不是列表。此外，您需要返回 for 循环之外的值。你可以试试下面的代码。

代码:

def GetInput():
    names = {}  # Needs to declare your dict
    percentages = {}  # Needs to declare your dict
    for counter in range(0, 3):
        names[counter] = input("Please enter the student's name: ")

        valid = False
        while valid == False:
            percentages[counter] = int(input("Please enter the student's score %: "))
            if percentages[counter] < 0 or percentages[counter] > 100:
                print("Please enter a valid % [0-100]")
            else:
                valid = True
    return names, percentages  # Return outside of for loop.

name, mark = GetInput()
print(name)
print(mark)

输出:

>>> python3 test.py 
Please enter the student's name: bob
Please enter the student's score %: 20
Please enter the student's name: ann
Please enter the student's score %: 30
Please enter the student's name: joe
Please enter the student's score %: 40
{0: 'bob', 1: 'ann', 2: 'joe'}
{0: 20, 1: 30, 2: 40}

如果你想创建一个包含学生姓名和百分比的通用字典，你可以尝试以下实现:

代码:

def GetInput():
    students = {}
    for _ in range(0, 3):
        student_name = input("Please enter the student's name: ")
        valid = False
        while not valid:
            student_percentages = int(input("Please enter the student's score %: "))
            if student_percentages < 0 or student_percentages > 100:
                print("Please enter a valid % [0-100]")
                continue
            valid = True
            students[student_name] = student_percentages
    return students


students = GetInput()
print(students)

输出:

>>> python3 test.py 
Please enter the student's name: ann
Please enter the student's score %: 20
Please enter the student's name: bob
Please enter the student's score %: 30
Please enter the student's name: joe
Please enter the student's score %: 40
{'ann': 20, 'bob': 30, 'joe': 40}