Python运行时错误，添加值列表时使用字典for循环

Question

我正试图在python 3.10中使用字典和列表制作联系人列表/电话簿，并一直试图添加一个功能来添加不在电话簿内的搜索联系人。我正在尝试的当前方法给了我"运行时错误:字典在迭代期间改变了大小"，所以我需要找到一种方法来添加字典而没有for循环，或者有人有任何建议吗?我很抱歉，如果这是简单的，或者我做的很少，因为我刚刚开始独立学习如何编码。谢谢你提供的任何帮助。下面是错误产生的部分:

from collections import defaultdict

#contact list using collection module
book = defaultdict(list)

search = input('Enter the name of the person you are looking for: ')
for key, value in book.items():
if key.startswith(search):
print(key, value)
else:
new_contact = input('That person is not in your contacts. Would you like to add them?(yes = y and no = n)')
if new_contact == 'y':
add_info = input('What is their contact information?')
book[search].append(add_info)
else:
break

Answer 1

假设你有一个像这样的字典book存在**book** = {'Alex' : 1234, 'Jane': 5694, ...}这应该有帮助:

一般来说，循环一个可迭代对象(列表，字典)并改变数据不是一个好主意。

book = {'Bill': 3456, 'Jane': 1298}
search = input('Enter the name of the person you are looking for: ')
if search in book:  
# found it   - if type either "Bill" or "Jane"
print(search, book[search])

else:  # anything else - not in the phonebook.
print(f'The {search} is not in the book')

action = input('That person is not in your contacts. Would you like to add them?(yes = y and no = n)')

if action == 'y':
add_info = input('What is the contact information? (name phone) ')
name, phone = add_info.split()
#book[name].append(phone)  # this Won't work. "Missing key"!
book.get(name, phone)