python之字典dict的for循环

以下方法等同，都可以获取key和value
1.#获取KEY和value
dir_test={ 'n':"psu",'v':"电压",'c':"电流"}
for key,value in dir_test.items():
   print(key,value)
2#获取KEY和value

for i,j in dir_test.items():
   #print("key:%s"%i,"value:%s"%dir_test[i])
   print("key:%s"%i,"value:%s"%j)

#获取value
for value in dir_test.values():
      print(value)
#获取key

for key in dir_test.keys():
   print(key)