from collections import defaultdict
num = input('>>>')
d1 = dict.fromkeys(num,0)
print(1,d1)
d2 = defaultdict(int)
for k in num:
print(2,'k:{} v:{}'.format(k,d2[k]))
d3 = {'a':1,'b':2}
print(3,d3.get('c',0))
d4 = {}
d4.setdefault('a',0)
print(4,d4)
运行结果:
>>>123
1 {'1': 0, '3': 0, '2': 0}
2 k:1 v:0
2 k:2 v:0
2 k:3 v:0
3 0
4 {'a': 0}
