Python字典增加键值对
类似于赋值，将值赋给不存在的键
代码：
person = {"name":"zhangsan", "age":18, "height":18}
print(person)
person["weight"] = "60kg"
print(person)
结果：
{‘name’: ‘zhangsan’, ‘age’: 18, ‘height’: 18}
{‘name’: ‘zhangsan’, ‘age’: 18, ‘height’: 18, ‘weight’: ’60kg’}
Python字典的删除键值对
有pop方法，popitem方法，clear方法与del（后两个不常用）
代码：
person = {"name":"zhangsan", "age":18, "height":18, "weight":"60kg"}
person.pop("age")
print(person)
person.popitem()
print(person)
person.clear()
print(person)
结果：
{‘name’: ‘zhangsan’, ‘height’: 18, ‘weight’: ’60kg’}
{‘name’: ‘zhangsan’, ‘height’: 18}
{}
Python字典修改键对应的值
和增加键的道理相同，为字典的键赋值，如果键存在则修改，不存在则添加
Python字典的查询
这里的查询指的是已知键查询对应的值
代码：
person = {"name":"zhangsan", "age":18, "height":18, "weight":"60kg"}
print(person["name"])
#返回的结果就是zhangsan