How to pass list in Python function?

After passing the list to the function, the function can directly access the contents of the list.

Suppose there is a group of experts and we want to invite them to a seminar.

def send_invitation(experts):
    '''发送邀请函'''
    for expert in experts:
        print(expert + '，您好，现邀请您参加 XX 研讨会...')

experts = ['小明', '小红']
send_invitation(experts)

Run results:

Hello Xiao Ming, you are now invited to participate in the XX seminar...

Hello Huang Lili, you are now invited to participate in the XX seminar Will...

1 Modify the list

After the list parameter is passed to the function, the function can modify it.

Note: Any modifications made to the list in the function are permanent.

def send_invitation(experts, informed):
    '''发送邀请函，并移动列表数据到【已通知】列表'''
    while experts:
        expert = experts.pop()
        print(expert + '，您好，现邀请您参加 XX 研讨会...')
        informed.append(expert)

experts = ['小明', '小红']  # 专家列表
informed = []  # 已通知人员列表
print('执行前：experts=' + str(experts) + ',informed=' + str(informed))
send_invitation(experts, informed)
print('执行后：experts=' + str(experts) + ',informed=' + str(informed))

Run results:

Before execution: experts=['Xiao Ming', 'Xiao Hong'], informed=[]

Hello Xiaohong , you are now invited to participate in the XX seminar...

Hello Xiaoming, you are now invited to participate in the XX seminar...

After execution: experts=[],informed=[' Xiaohong', 'Xiaoming']

Even without comments, descriptive function names can clearly express the work done by the function.
We can also call another function within a function, which helps break down complex tasks into a series of steps and makes the program more readable.

2 Read-only list

Sometimes, we don’t want the function to modify the passed list,

In this case we can pass a copy of the list to the function:

experts = ['小明', '小红']  # 专家列表
informed = []  # 已通知人员列表
print('执行前：experts=' + str(experts) + ',informed=' + str(informed))
send_invitation(experts[:], informed)
print('执行后：experts=' + str(experts) + ',informed=' + str(informed))

Run result:

Before execution: experts=['Xiao Ming', 'Xiao Hong'], informed=[]

Xiaohong, hello, now inviting You are attending the XX seminar...

Hello Xiao Ming, you are now invited to attend the XX seminar...

After execution: experts=['Xiao Ming', 'Xiao Hong'] ,informed=['小红', '小明']

Although passing a copy of the list to the function can preserve the contents of the original list,

Unless there is a good reason to do so Do.

Because having the function use a passed list can improve performance by avoiding spending time

creating a copy in memory, which is especially important when dealing with large data lists.

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