字典的基本操作及循环

stu_name = {'libo':'85','lihuiting':'90','liguobing':'80'}#定义一个字典 key-value形式存储的

print(stu_name)
#曾
stu_name['xiaohong'] = '95'#增加一个元素
stu_name.setdefault('xiaobei','77')#增加一个元素
print(stu_name)#从打印的结果来看字典是无序的

#修改
stu_name['libo']='90' #把libo的value改成90
print(stu_name)

#删除一个值
stu_name.pop('xiaohong')#指定一个key来进行删除
print(stu_name)
stu_name.popitem()#随机删除一个值
print(stu_name)
del stu_name['libo']#指定一个key来进行删除
print(stu_name)
stu_name.clear()
print(stu_name)#清除一个字典

#查看一个值
stu_name = {'libo':'85','lihuiting':'90','liguobing':'80'}
print(stu_name.keys())#获取字典的所有的key
print(stu_name.values())#获取字典的所有value
print(stu_name.items())#获取字典所有的key-value

print(stu_name.get('phone'))#取不到这个key的话，就是None
print(stu_name.get('phone',110))#如果取不到这个key的话，默认就是110
print(stu_name['phone'])#如果key不存在会报错

#循环字典
for i in stu_name: #直接循环只是循环的key
 print(i)
for k, v in stu_name.items():#循环字段中的key-value
 print(k,v)

#字典的嵌套循环

name = {'libo':'90','test':'100','xunhuan':{'test11':'99','test222':'88'}}

for k,v in name.items():
 if type(v)== dict:
 for i in v:
 print(i)
 print(k,v)