dict 字典类型的强制转换
"""
要求: 必须是等长的二级容器,并且里面的元素个数是2个;
外层是列表,元组,集合 , 里层是列表或者元组的等长二级容器 => 字典;
"""

# 1.外层是列表,里层是列表或者元组
lst = [ ["a",1] , ("b",2) ]
dic = dict(lst)
print(dic , type(dic)) # {'a': 1, 'b': 2} <class 'dict'>

# 2.外层是元组,里层是列表或者元组
tup = ( ["a",1] , ("b",2) )
dic = dict(tup)
print(dic , type(dic))

# 3.外层是集合,里层是元组
setvar = { ("a",1) , ("b",2) }
dic = dict(setvar)
print(dic , type(dic))

# 例外1:外层是列表/元组,里层放集合
"""可以实现,不推荐使用,因为达不到想要的目的,集合无序,不推荐使用"""
lst = [ ["a",1] , {"b","250"} ]
dic = dict(lst)
print(dic)

# 例外2:外层是列表/元组,里层放字符串
""" 字符串长度只能是2位,有极大的局限性,不推荐使用"""
lst = ["a1","b2"]
# lst = ["a11","b22"] error 
# dic = dict(lst)
# print(dic)