Python数据类型详解（四）字典：dict

class dict(object):  """  dict() -> new empty dictionary  dict(mapping) -> new dictionary initialized from a mapping object's    (key, value) pairs  dict(iterable) -> new dictionary initialized as if via:    d = {}    for k, v in iterable:      d[k] = v  dict(**kwargs) -> new dictionary initialized with the name=value pairs    in the keyword argument list. For example: dict(one=1, two=2)  """  def clear(self): # real signature unknown; restored from __doc__    """ D.clear() -> None. Remove all items from D. """    pass  def copy(self): # real signature unknown; restored from __doc__    """ D.copy() -> a shallow copy of D """    pass  @staticmethod # known case  def fromkeys(*args, **kwargs): # real signature unknown    """ Returns a new dict with keys from iterable and values equal to value. """    pass  def get(self, k, d=None): # real signature unknown; restored from __doc__    """ D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None. """    pass  def items(self): # real signature unknown; restored from __doc__    """ D.items() -> a set-like object providing a view on D's items """    pass  def keys(self): # real signature unknown; restored from __doc__    """ D.keys() -> a set-like object providing a view on D's keys """    pass  def pop(self, k, d=None): # real signature unknown; restored from __doc__    """    D.pop(k[,d]) -> v, remove specified key and return the corresponding value.    If key is not found, d is returned if given, otherwise KeyError is raised    """    pass  def popitem(self): # real signature unknown; restored from __doc__    """    D.popitem() -> (k, v), remove and return some (key, value) pair as a    2-tuple; but raise KeyError if D is empty.    """    pass  def setdefault(self, k, d=None): # real signature unknown; restored from __doc__    """ D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """    pass  def update(self, E=None, **F): # known special case of dict.update    """    D.update([E, ]**F) -> None. Update D from dict/iterable E and F.    If E is present and has a .keys() method, then does: for k in E: D[k] = E[k]    If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v    In either case, this is followed by: for k in F: D[k] = F[k]    """    pass  def values(self): # real signature unknown; restored from __doc__    """ D.values() -> an object providing a view on D's values """    pass  def __contains__(self, *args, **kwargs): # real signature unknown    """ True if D has a key k, else False. """    pass  def __delitem__(self, *args, **kwargs): # real signature unknown    """ Delete self[key]. """    pass  def __eq__(self, *args, **kwargs): # real signature unknown    """ Return self==value. """    pass  def __getattribute__(self, *args, **kwargs): # real signature unknown    """ Return getattr(self, name). """    pass  def __getitem__(self, y): # real signature unknown; restored from __doc__    """ x.__getitem__(y) <==> x[y] """    pass  def __ge__(self, *args, **kwargs): # real signature unknown    """ Return self>=value. """    pass  def __gt__(self, *args, **kwargs): # real signature unknown    """ Return self>value. """    pass  def __init__(self, seq=None, **kwargs): # known special case of dict.__init__    """    dict() -> new empty dictionary    dict(mapping) -> new dictionary initialized from a mapping object's      (key, value) pairs    dict(iterable) -> new dictionary initialized as if via:      d = {}      for k, v in iterable:        d[k] = v    dict(**kwargs) -> new dictionary initialized with the name=value pairs      in the keyword argument list. For example: dict(one=1, two=2)    # (copied from class doc)    """    pass  def __iter__(self, *args, **kwargs): # real signature unknown    """ Implement iter(self). """    pass  def __len__(self, *args, **kwargs): # real signature unknown    """ Return len(self). """    pass  def __le__(self, *args, **kwargs): # real signature unknown    """ Return self<=value. """    pass  def __lt__(self, *args, **kwargs): # real signature unknown    """ Return self<value. """    pass  @staticmethod # known case of __new__  def __new__(*args, **kwargs): # real signature unknown    """ Create and return a new object. See help(type) for accurate signature. """    pass  def __ne__(self, *args, **kwargs): # real signature unknown    """ Return self!=value. """    pass  def __repr__(self, *args, **kwargs): # real signature unknown    """ Return repr(self). """    pass  def __setitem__(self, *args, **kwargs): # real signature unknown    """ Set self[key] to value. """    pass  def __sizeof__(self): # real signature unknown; restored from __doc__    """ D.__sizeof__() -> size of D in memory, in bytes """    pass  __hash__ = None

user_info = {  0 :"zhangyanlin",  "age" :"18",  2 :"pythoner"}#获取所有的keyprint(user_info.keys()) #获取所有的valuesprint(user_info.values()) #获取所有的key和valuesprint(user_info.items()) clear清除所有的内容user_info.clear()print(user_info) #get 根据key获取值，如果key不存在，可以指定一个默认值val = user_info.get('age')print(val)#update批量更新test = {  'a':111,  'b':222}user_info.update(test)print(user_info)

#如果没有key，会报错user_info = {  "name" :'zhangyanlin',  "age" :18,  "job" :'pythoner'}print(user_info['name'])

#循环user_info = {  0 :"zhangyanlin",  "age" :"18",  2 :"pythoner"}for i in user_info:  print(i) #循环输出所有的键入值for k,v in user_info.items():  print(k)  print(v)