python基础-字典类型的demo

# 创建字典
dic = dict()
dic['a'] = 'aa'
dic['b'] = 'bb'
dic['c'] = 'cc'
dic['d'] = 'dd'
dic['e'] = 'ee'
dic['f'] = 'ff'
print(dic)

# 删除
dic.pop('a')
print(dic)

# 查询
print(dic['z']) # key不存在报错，当确定key存在时可以用
print(dic.get('z'))  # key不存在返回None，不报错

# a = None
# print(type(a))  # <class 'NoneType'>

# 字典循环遍历
for key in dic:
    print(key)

# 特色方法
print(dic.keys())
print(list(dic.keys()))
print(dic.values())
print(list(dic.values()))
print(dic.items())
print(list(dic.items()))

for k, v in dic.items():
    print(k, v)

a, b = (1, 2)  # 解构/解包
print(a, b)