Python 我得到了'；无'；在我运行的每个打印语句末尾打印。我不完全清楚为什么？

调用函数时，不要添加打印。只需调用函数即可

def finished_projects(unfinished_projects, completed_projects):
    while unfinished_projects:
        current_project = unfinished_projects.pop()
        print('completing project: ' + current_project)
        completed_projects.append(current_project)

def show_completed_projects(completed_projects):
    print('\nThese projects have been completed:')
    for project in completed_projects:
        print(project)
    

unfinished_projects = ['pie-chart', 'bar graph', 'line chart']
completed_projects = []

print(finished_projects(unfinished_projects,completed_projects))
print(show_completed_projects(completed_projects))

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如果您返回了一些内容，则可以使用“打印”。

这是因为您试图打印两个函数的返回值，而这两个函数都没有，请尝试执行以下操作：

def finished_projects(unfinished_projects, completed_projects):
    while unfinished_projects:
        current_project = unfinished_projects.pop()
        print('completing project: ' + current_project)
        completed_projects.append(current_project)

def show_completed_projects(completed_projects):
    print('\nThese projects have been completed:')
    for project in completed_projects:
        print(project)
    

unfinished_projects = ['pie-chart', 'bar graph', 'line chart']
completed_projects = []

finished_projects(unfinished_projects,completed_projects)
show_completed_projects(completed_projects)

---

因为这两个函数都没有返回任何内容。您正在从函数内部打印。您的函数返回

None

，因此当您调用时，例如，

print（show_completed_projects（…）

打印的是返回值

None

。

finished_projects(unfinished_projects,completed_projects)
show_completed_projects(completed_projects)