字典

# 字典 dict {}
# key:value形式存储
# 可以空字典
# value可以包含任何类型数据
# 逗号分隔键值对
# len()查看长度
# 字典无序，不按顺序输出
# 字典取值 字典[key]
a = {"class": "python11",
     "student": 119,
     "teacher": "girl",
     "t_age": 20,
     "score": [90, 70, 80]}
print(len(a))
print(a)
print(a["score"])

# 删除 pop(key) 必须指定key
res = a.pop("teacher")
print(a)
print(res)

# 新增 a[新key]=value
a["name"] = "lemon"
print(a)

# 修改 a[已有的key]=新的value
a["t_age"] = 15
print(a)

# 存在相同key时，最后key的值会覆盖前面的
# 不要存在相同的key
# 存放不同数据类型时，使用字典
a = {"class": "python11",
     "student": 119,
     "teacher": "girl",
     "t_age": 20,
     "score": [90, 70, 80],
     "student": 125}
print(a)