Python 中的字典和带值的键

Question

I have to create a program which will print a greeting only to friendly bears. I have created this program but it gives me all the bears, the angry ones too.

bears = {"Grizzly":"angry", "Brown":"friendly", "Polar":"friendly"}
for bear in bears:
  if "[bear]:friendly":
   print("Hello, "+bear+" bear!")
else:
  print("odd")

Answer 1

I think it is a better idea to iterate over dict 's keys' and values by items() method (or iteritems() if you are using python2 ):

for bear_name, status in bears.items():  # get key and value for bear
    if status == 'friendly':
        print("Hello, " + bear_name + " bear!")

And polar bears are usually not friendly.

Answer 2

You can use this approach :

bears = {"Grizzly":"angry", "Brown":"friendly", "Polar":"friendly"}

for i,j in bears.items():
    if j=="friendly":
        print("Hello, " + i + " bear!")
    else:
        print('odd')

output:

odd
Hello, Polar bear!
Hello, Brown bear!

Answer 3

You can use the following, which should give you the output you want:

for bear in bears:
if bears[bear] == "friendly":
    print("Hello, " + bear + " bear!")
else:
    print("odd")