往dictionary加新的key，为什么要在前面加def

Question

问题是，已经有了一个字典叫travel_log，然后我想加新的key进去，但是为什么要在空字典new_country前面加一个def呢，为什么不直接写一个空的字典然后直接赋值，我知道我的不对，但是我不明白为什么要加def

我的

travel_log = [
{
  "country": "France",
  "visits": 12,
  "cities": ["Paris", "Lille", "Dijon"]
},
{
  "country": "Germany",
  "visits": 5,
  "cities": ["Berlin", "Hamburg", "Stuttgart"]
},
]

#TODO: Write the function that will allow new countries
#to be added to the travel_log. 👇

  new_country = {}
  new_country["country"] = Russia
  new_country["visits"] = 12
  new_country["cities"] = Moscow, Saint Petersburg
  travel_log.append(new_country)

print(travel_log)

正确的

travel_log = [
{
  "country": "France",
  "visits": 12,
  "cities": ["Paris", "Lille", "Dijon"]
},
{
  "country": "Germany",
  "visits": 5,
  "cities": ["Berlin", "Hamburg", "Stuttgart"]
},
]

#TODO: Write the function that will allow new countries
#to be added to the travel_log. 👇

def add_new_country(country_visits, times, cities_visits):
  new_country = {}
  new_country["country"] = country_visits
  new_country["visits"] = times
  new_country["cities"] = cities_visits
  travel_log.append(new_country)

add_new_country("Russia", 2, ["Moscow", "Saint Petersburg"])
print(travel_log)

Answer 1

这其实并不是def的问题，而是python基础语法 缩进的问题

def foo():
····pass

这四个点就代表四个空格，你可以把 所有缩进去掉 同时去掉def 其他语言中语法块用{ } 这种 python中用四个空格，四个空格代表 一个作用域，下面这样去掉def的作用域也是可以的

travel_log = [
    {
        "country": "France",
        "visits": 12,
        "cities": ["Paris", "Lille", "Dijon"]
    },
    {
        "country": "Germany",
        "visits": 5,
        "cities": ["Berlin", "Hamburg", "Stuttgart"]
    },
]


# TODO: Write the function that will allow new countries
# to be added to the travel_log. 👇


new_country = {}
new_country["country"] = "Russia"
new_country["visits"] = 2
new_country["cities"] = ["Moscow", "Saint Petersburg"]
travel_log.append(new_country)

print(travel_log)