36.

37.

38.

39.

40.

字典和列表的不同在于，它的索引可以是任意类型的

>>> haha={'a':1,'b':2,'c':3}

>>> print(haha['a'])

1

>>> print(haha['b'])

2

>>> print(haha['c'])

3

>>> haha['d']=4  #在字典中添加元素

>>> print(haha['d'])

4

>>> print(haha)  #输出字典

{'b': 2, 'c': 3, 'd': 4, 'a': 1}

还有这种操作：

>>> haha[1]='sb'

>>> haha[2]='SB'

>>> print(haha)

{1: 'sb', 2: 'SB', 'c': 3, 'b': 2, 'd': 4, 'a': 1}

删除字典中的元素：关键字del

>>> print(haha)

{1: 'sb', 2: 'SB', 'c': 3, 'b': 2, 'd': 4, 'a': 1}

>>> del haha['a']

>>> print(haha)

{1: 'sb', 2: 'SB', 'c': 3, 'b': 2, 'd': 4}

>>> del haha[1]

>>> print(haha)

{2: 'SB', 'c': 3, 'b': 2, 'd': 4}

这是一个重要的例题

cities = {
   'CA': 'San Francisco', 'MI': 'Detroit','FL': 'Jacksonville'}cities['NY'] = 'New York'cities['OR'] = 'Portland'def find_city(themap, state):    if state in themap:  #看最后的例子        return themap[state]    else:        return "Not found."cities['_find'] = find_city  #这里把函数名当做变量，如果这句写在函数之前就会报错while True:    print "State? (ENTER to quit)",    state = raw_input("> ")    if not state: break   #当没有录入时state为''或者None此时not state为True    city_found = cities['_find'](cities, state)

print city_found

>>> not ''

True

>>> not 123

False

>>> not'12'

False

>>> not None

True

>>> haha={'a':1,'b':2,'c':3}

>>> 'a' in haha

True