运算符

1、算数运算：

2、比较运算：

3、赋值运算：

4、逻辑运算：

5、成员运算：

基本数据类型：

数字【int】：        12，3456789，3334

字符串【str】：     “asdfghkj”，“qwe”

布尔值【bool】：     True，False

列表【list】：          [("123"),("adsf")]

元组【tuple】：     (1,2,3,4,5)

字典【dict】：          {(123),(asd)}

基本数据数据类型常用功能

1.【整数】，int

a.
          #  n1 = 123
          #  n2 = 456
          #  print(n1 + n2)
          #  print(n1._add_(n2))
     b.
        获取可表示的二进制最短位数
           # n1 = 4 # 000000100
           # ret = n1.bit_length()
           # print(ret)

class int(object):
    """
    int(x=0) -> int or long
    int(x, base=10) -> int or long

    Convert a number or string to an integer, or return 0 if no arguments
    are given.  If x is floating point, the conversion truncates towards zero.
    If x is outside the integer range, the function returns a long instead.

    If x is not a number or if base is given, then x must be a string or
    Unicode object representing an integer literal in the given base.  The
    literal can be preceded by ‘+‘ or ‘-‘ and be surrounded by whitespace.
    The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
    interpret the base from the string as an integer literal.
    >>> int(‘0b100‘, base=0)
    4
    """
    def bit_length(self):
        """ 返回表示该数字的时占用的最少位数 """
        """
        int.bit_length() -> int

        Number of bits necessary to represent self in binary.
        >>> bin(37)
        ‘0b100101‘
        >>> (37).bit_length()
        6
        """
        return 0

    def conjugate(self, *args, **kwargs): # real signature unknown
        """ 返回该复数的共轭复数 """
        """ Returns self, the complex conjugate of any int. """
        pass

    def __abs__(self):
        """ 返回绝对值 """
        """ x.__abs__() <==> abs(x) """
        pass

    def __add__(self, y):
        """ x.__add__(y) <==> x+y """
        pass

    def __and__(self, y):
        """ x.__and__(y) <==> x&y """
        pass

    def __cmp__(self, y):
        """ 比较两个数大小 """
        """ x.__cmp__(y) <==> cmp(x,y) """
        pass

    def __coerce__(self, y):
        """ 强制生成一个元组 """
        """ x.__coerce__(y) <==> coerce(x, y) """
        pass

    def __divmod__(self, y):
        """ 相除，得到商和余数组成的元组 """
        """ x.__divmod__(y) <==> divmod(x, y) """
        pass

    def __div__(self, y):
        """ x.__div__(y) <==> x/y """
        pass

    def __float__(self):
        """ 转换为浮点类型 """
        """ x.__float__() <==> float(x) """
        pass

    def __floordiv__(self, y):
        """ x.__floordiv__(y) <==> x//y """
        pass

    def __format__(self, *args, **kwargs): # real signature unknown
        pass

    def __getattribute__(self, name):
        """ x.__getattribute__(‘name‘) <==> x.name """
        pass

    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        """ 内部调用 __new__方法或创建对象时传入参数使用 """
        pass

    def __hash__(self):
        """如果对象object为哈希表类型，返回对象object的哈希值。哈希值为整数。在字典查找中，哈希值用于快速比较字典的键。两个数值如果相等，则哈希值也相等。"""
        """ x.__hash__() <==> hash(x) """
        pass

    def __hex__(self):
        """ 返回当前数的 十六进制 表示 """
        """ x.__hex__() <==> hex(x) """
        pass

    def __index__(self):
        """ 用于切片，数字无意义 """
        """ x[y:z] <==> x[y.__index__():z.__index__()] """
        pass

    def __init__(self, x, base=10): # known special case of int.__init__
        """ 构造方法，执行 x = 123 或 x = int(10) 时，自动调用，暂时忽略 """
        """
        int(x=0) -> int or long
        int(x, base=10) -> int or long

        Convert a number or string to an integer, or return 0 if no arguments
        are given.  If x is floating point, the conversion truncates towards zero.
        If x is outside the integer range, the function returns a long instead.

        If x is not a number or if base is given, then x must be a string or
        Unicode object representing an integer literal in the given base.  The
        literal can be preceded by ‘+‘ or ‘-‘ and be surrounded by whitespace.
        The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
        interpret the base from the string as an integer literal.
        >>> int(‘0b100‘, base=0)
        4
        # (copied from class doc)
        """
        pass

    def __int__(self):
        """ 转换为整数 """
        """ x.__int__() <==> int(x) """
        pass

    def __invert__(self):
        """ x.__invert__() <==> ~x """
        pass

    def __long__(self):
        """ 转换为长整数 """
        """ x.__long__() <==> long(x) """
        pass

    def __lshift__(self, y):
        """ x.__lshift__(y) <==> x<<y """
        pass

    def __mod__(self, y):
        """ x.__mod__(y) <==> x%y """
        pass

    def __mul__(self, y):
        """ x.__mul__(y) <==> x*y """
        pass

    def __neg__(self):
        """ x.__neg__() <==> -x """
        pass

    @staticmethod # known case of __new__
    def __new__(S, *more):
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass

    def __nonzero__(self):
        """ x.__nonzero__() <==> x != 0 """
        pass

    def __oct__(self):
        """ 返回改值的 八进制 表示 """
        """ x.__oct__() <==> oct(x) """
        pass

    def __or__(self, y):
        """ x.__or__(y) <==> x|y """
        pass

    def __pos__(self):
        """ x.__pos__() <==> +x """
        pass

    def __pow__(self, y, z=None):
        """ 幂，次方 """
        """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """
        pass

    def __radd__(self, y):
        """ x.__radd__(y) <==> y+x """
        pass

    def __rand__(self, y):
        """ x.__rand__(y) <==> y&x """
        pass

    def __rdivmod__(self, y):
        """ x.__rdivmod__(y) <==> divmod(y, x) """
        pass

    def __rdiv__(self, y):
        """ x.__rdiv__(y) <==> y/x """
        pass

    def __repr__(self):
        """转化为解释器可读取的形式 """
        """ x.__repr__() <==> repr(x) """
        pass

    def __str__(self):
        """转换为人阅读的形式，如果没有适于人阅读的解释形式的话，则返回解释器课阅读的形式"""
        """ x.__str__() <==> str(x) """
        pass

    def __rfloordiv__(self, y):
        """ x.__rfloordiv__(y) <==> y//x """
        pass

    def __rlshift__(self, y):
        """ x.__rlshift__(y) <==> y<<x """
        pass

    def __rmod__(self, y):
        """ x.__rmod__(y) <==> y%x """
        pass

    def __rmul__(self, y):
        """ x.__rmul__(y) <==> y*x """
        pass

    def __ror__(self, y):
        """ x.__ror__(y) <==> y|x """
        pass

    def __rpow__(self, x, z=None):
        """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """
        pass

    def __rrshift__(self, y):
        """ x.__rrshift__(y) <==> y>>x """
        pass

    def __rshift__(self, y):
        """ x.__rshift__(y) <==> x>>y """
        pass

    def __rsub__(self, y):
        """ x.__rsub__(y) <==> y-x """
        pass

    def __rtruediv__(self, y):
        """ x.__rtruediv__(y) <==> y/x """
        pass

    def __rxor__(self, y):
        """ x.__rxor__(y) <==> y^x """
        pass

    def __sub__(self, y):
        """ x.__sub__(y) <==> x-y """
        pass

    def __truediv__(self, y):
        """ x.__truediv__(y) <==> x/y """
        pass

    def __trunc__(self, *args, **kwargs):
        """ 返回数值被截取为整形的值，在整形中无意义 """
        pass

    def __xor__(self, y):
        """ x.__xor__(y) <==> x^y """
        pass

    denominator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 分母 = 1 """
    """the denominator of a rational number in lowest terms"""

    imag = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 虚数，无意义 """
    """the imaginary part of a complex number"""

    numerator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 分子 = 数字大小 """
    """the numerator of a rational number in lowest terms"""

    real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 实属，无意义 """
    """the real part of a complex number"""

int

2.【字符串】，str

字符串常用功能：

• 移除空白
• 分割
• 长度
• 索引
• 切片

class str(basestring):
    """
    str(object=‘‘) -> string

    Return a nice string representation of the object.
    If the argument is a string, the return value is the same object.
    """
    def capitalize(self):
        """ 首字母变大写 """
        """
        S.capitalize() -> string

        Return a copy of the string S with only its first character
        capitalized.
        """
        return ""

    def center(self, width, fillchar=None):
        """ 内容居中，width：总长度；fillchar：空白处填充内容，默认无 """
        """
        S.center(width[, fillchar]) -> string

        Return S centered in a string of length width. Padding is
        done using the specified fill character (default is a space)
        """
        return ""

    def count(self, sub, start=None, end=None):
        """ 子序列个数 """
        """
        S.count(sub[, start[, end]]) -> int

        Return the number of non-overlapping occurrences of substring sub in
        string S[start:end].  Optional arguments start and end are interpreted
        as in slice notation.
        """
        return 0

    def decode(self, encoding=None, errors=None):
        """ 解码 """
        """
        S.decode([encoding[,errors]]) -> object

        Decodes S using the codec registered for encoding. encoding defaults
        to the default encoding. errors may be given to set a different error
        handling scheme. Default is ‘strict‘ meaning that encoding errors raise
        a UnicodeDecodeError. Other possible values are ‘ignore‘ and ‘replace‘
        as well as any other name registered with codecs.register_error that is
        able to handle UnicodeDecodeErrors.
        """
        return object()

    def encode(self, encoding=None, errors=None):
        """ 编码，针对unicode """
        """
        S.encode([encoding[,errors]]) -> object

        Encodes S using the codec registered for encoding. encoding defaults
        to the default encoding. errors may be given to set a different error
        handling scheme. Default is ‘strict‘ meaning that encoding errors raise
        a UnicodeEncodeError. Other possible values are ‘ignore‘, ‘replace‘ and
        ‘xmlcharrefreplace‘ as well as any other name registered with
        codecs.register_error that is able to handle UnicodeEncodeErrors.
        """
        return object()

    def endswith(self, suffix, start=None, end=None):
        """ 是否以 xxx 结束 """
        """
        S.endswith(suffix[, start[, end]]) -> bool

        Return True if S ends with the specified suffix, False otherwise.
        With optional start, test S beginning at that position.
        With optional end, stop comparing S at that position.
        suffix can also be a tuple of strings to try.
        """
        return False

    def expandtabs(self, tabsize=None):
        """ 将tab转换成空格，默认一个tab转换成8个空格 """
        """
        S.expandtabs([tabsize]) -> string

        Return a copy of S where all tab characters are expanded using spaces.
        If tabsize is not given, a tab size of 8 characters is assumed.
        """
        return ""

    def find(self, sub, start=None, end=None):
        """ 寻找子序列位置，如果没找到，返回 -1 """
        """
        S.find(sub [,start [,end]]) -> int

        Return the lowest index in S where substring sub is found,
        such that sub is contained within S[start:end].  Optional
        arguments start and end are interpreted as in slice notation.

        Return -1 on failure.
        """
        return 0

    def format(*args, **kwargs): # known special case of str.format
        """ 字符串格式化，动态参数，将函数式编程时细说 """
        """
        S.format(*args, **kwargs) -> string

        Return a formatted version of S, using substitutions from args and kwargs.
        The substitutions are identified by braces (‘{‘ and ‘}‘).
        """
        pass

    def index(self, sub, start=None, end=None):
        """ 子序列位置，如果没找到，报错 """
        S.index(sub [,start [,end]]) -> int

        Like S.find() but raise ValueError when the substring is not found.
        """
        return 0

    def isalnum(self):
        """ 是否是字母和数字 """
        """
        S.isalnum() -> bool

        Return True if all characters in S are alphanumeric
        and there is at least one character in S, False otherwise.
        """
        return False

    def isalpha(self):
        """ 是否是字母 """
        """
        S.isalpha() -> bool

        Return True if all characters in S are alphabetic
        and there is at least one character in S, False otherwise.
        """
        return False

    def isdigit(self):
        """ 是否是数字 """
        """
        S.isdigit() -> bool

        Return True if all characters in S are digits
        and there is at least one character in S, False otherwise.
        """
        return False

    def islower(self):
        """ 是否小写 """
        """
        S.islower() -> bool

        Return True if all cased characters in S are lowercase and there is
        at least one cased character in S, False otherwise.
        """
        return False

    def isspace(self):
        """
        S.isspace() -> bool

        Return True if all characters in S are whitespace
        and there is at least one character in S, False otherwise.
        """
        return False

    def istitle(self):
        """
        S.istitle() -> bool

        Return True if S is a titlecased string and there is at least one
        character in S, i.e. uppercase characters may only follow uncased
        characters and lowercase characters only cased ones. Return False
        otherwise.
        """
        return False

    def isupper(self):
        """
        S.isupper() -> bool

        Return True if all cased characters in S are uppercase and there is
        at least one cased character in S, False otherwise.
        """
        return False

    def join(self, iterable):
        """ 连接 """
        """
        S.join(iterable) -> string

        Return a string which is the concatenation of the strings in the
        iterable.  The separator between elements is S.
        """
        return ""

    def ljust(self, width, fillchar=None):
        """ 内容左对齐，右侧填充 """
        """
        S.ljust(width[, fillchar]) -> string

        Return S left-justified in a string of length width. Padding is
        done using the specified fill character (default is a space).
        """
        return ""

    def lower(self):
        """ 变小写 """
        """
        S.lower() -> string

        Return a copy of the string S converted to lowercase.
        """
        return ""

    def lstrip(self, chars=None):
        """ 移除左侧空白 """
        """
        S.lstrip([chars]) -> string or unicode

        Return a copy of the string S with leading whitespace removed.
        If chars is given and not None, remove characters in chars instead.
        If chars is unicode, S will be converted to unicode before stripping
        """
        return ""

    def partition(self, sep):
        """ 分割，前，中，后三部分 """
        """
        S.partition(sep) -> (head, sep, tail)

        Search for the separator sep in S, and return the part before it,
        the separator itself, and the part after it.  If the separator is not
        found, return S and two empty strings.
        """
        pass

    def replace(self, old, new, count=None):
        """ 替换 """
        """
        S.replace(old, new[, count]) -> string

        Return a copy of string S with all occurrences of substring
        old replaced by new.  If the optional argument count is
        given, only the first count occurrences are replaced.
        """
        return ""

    def rfind(self, sub, start=None, end=None):
        """
        S.rfind(sub [,start [,end]]) -> int

        Return the highest index in S where substring sub is found,
        such that sub is contained within S[start:end].  Optional
        arguments start and end are interpreted as in slice notation.

        Return -1 on failure.
        """
        return 0

    def rindex(self, sub, start=None, end=None):
        """
        S.rindex(sub [,start [,end]]) -> int

        Like S.rfind() but raise ValueError when the substring is not found.
        """
        return 0

    def rjust(self, width, fillchar=None):
        """
        S.rjust(width[, fillchar]) -> string

        Return S right-justified in a string of length width. Padding is
        done using the specified fill character (default is a space)
        """
        return ""

    def rpartition(self, sep):
        """
        S.rpartition(sep) -> (head, sep, tail)

        Search for the separator sep in S, starting at the end of S, and return
        the part before it, the separator itself, and the part after it.  If the
        separator is not found, return two empty strings and S.
        """
        pass

    def rsplit(self, sep=None, maxsplit=None):
        """
        S.rsplit([sep [,maxsplit]]) -> list of strings

        Return a list of the words in the string S, using sep as the
        delimiter string, starting at the end of the string and working
        to the front.  If maxsplit is given, at most maxsplit splits are
        done. If sep is not specified or is None, any whitespace string
        is a separator.
        """
        return []

    def rstrip(self, chars=None):
        """
        S.rstrip([chars]) -> string or unicode

        Return a copy of the string S with trailing whitespace removed.
        If chars is given and not None, remove characters in chars instead.
        If chars is unicode, S will be converted to unicode before stripping
        """
        return ""

    def split(self, sep=None, maxsplit=None):
        """ 分割， maxsplit最多分割几次 """
        """
        S.split([sep [,maxsplit]]) -> list of strings

        Return a list of the words in the string S, using sep as the
        delimiter string.  If maxsplit is given, at most maxsplit
        splits are done. If sep is not specified or is None, any
        whitespace string is a separator and empty strings are removed
        from the result.
        """
        return []

    def splitlines(self, keepends=False):
        """ 根据换行分割 """
        """
        S.splitlines(keepends=False) -> list of strings

        Return a list of the lines in S, breaking at line boundaries.
        Line breaks are not included in the resulting list unless keepends
        is given and true.
        """
        return []

    def startswith(self, prefix, start=None, end=None):
        """ 是否起始 """
        """
        S.startswith(prefix[, start[, end]]) -> bool

        Return True if S starts with the specified prefix, False otherwise.
        With optional start, test S beginning at that position.
        With optional end, stop comparing S at that position.
        prefix can also be a tuple of strings to try.
        """
        return False

    def strip(self, chars=None):
        """ 移除两段空白 """
        """
        S.strip([chars]) -> string or unicode

        Return a copy of the string S with leading and trailing
        whitespace removed.
        If chars is given and not None, remove characters in chars instead.
        If chars is unicode, S will be converted to unicode before stripping
        """
        return ""

    def swapcase(self):
        """ 大写变小写，小写变大写 """
        """
        S.swapcase() -> string

        Return a copy of the string S with uppercase characters
        converted to lowercase and vice versa.
        """
        return ""

    def title(self):
        """
        S.title() -> string

        Return a titlecased version of S, i.e. words start with uppercase
        characters, all remaining cased characters have lowercase.
        """
        return ""

    def translate(self, table, deletechars=None):
        """
        转换，需要先做一个对应表，最后一个表示删除字符集合
        intab = "aeiou"
        outtab = "12345"
        trantab = maketrans(intab, outtab)
        str = "this is string example....wow!!!"
        print str.translate(trantab, ‘xm‘)
        """

        """
        S.translate(table [,deletechars]) -> string

        Return a copy of the string S, where all characters occurring
        in the optional argument deletechars are removed, and the
        remaining characters have been mapped through the given
        translation table, which must be a string of length 256 or None.
        If the table argument is None, no translation is applied and
        the operation simply removes the characters in deletechars.
        """
        return ""

    def upper(self):
        """
        S.upper() -> string

        Return a copy of the string S converted to uppercase.
        """
        return ""

    def zfill(self, width):
        """方法返回指定长度的字符串，原字符串右对齐，前面填充0。"""
        """
        S.zfill(width) -> string

        Pad a numeric string S with zeros on the left, to fill a field
        of the specified width.  The string S is never truncated.
        """
        return ""

    def _formatter_field_name_split(self, *args, **kwargs): # real signature unknown
        pass

    def _formatter_parser(self, *args, **kwargs): # real signature unknown
        pass

    def __add__(self, y):
        """ x.__add__(y) <==> x+y """
        pass

    def __contains__(self, y):
        """ x.__contains__(y) <==> y in x """
        pass

    def __eq__(self, y):
        """ x.__eq__(y) <==> x==y """
        pass

    def __format__(self, format_spec):
        """
        S.__format__(format_spec) -> string

        Return a formatted version of S as described by format_spec.
        """
        return ""

    def __getattribute__(self, name):
        """ x.__getattribute__(‘name‘) <==> x.name """
        pass

    def __getitem__(self, y):
        """ x.__getitem__(y) <==> x[y] """
        pass

    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        pass

    def __getslice__(self, i, j):
        """
        x.__getslice__(i, j) <==> x[i:j]

                   Use of negative indices is not supported.
        """
        pass

    def __ge__(self, y):
        """ x.__ge__(y) <==> x>=y """
        pass

    def __gt__(self, y):
        """ x.__gt__(y) <==> x>y """
        pass

    def __hash__(self):
        """ x.__hash__() <==> hash(x) """
        pass

    def __init__(self, string=‘‘): # known special case of str.__init__
        """
        str(object=‘‘) -> string

        Return a nice string representation of the object.
        If the argument is a string, the return value is the same object.
        # (copied from class doc)
        """
        pass

    def __len__(self):
        """ x.__len__() <==> len(x) """
        pass

    def __le__(self, y):
        """ x.__le__(y) <==> x<=y """
        pass

    def __lt__(self, y):
        """ x.__lt__(y) <==> x<y """
        pass

    def __mod__(self, y):
        """ x.__mod__(y) <==> x%y """
        pass

    def __mul__(self, n):
        """ x.__mul__(n) <==> x*n """
        pass

    @staticmethod # known case of __new__
    def __new__(S, *more):
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass

    def __ne__(self, y):
        """ x.__ne__(y) <==> x!=y """
        pass

    def __repr__(self):
        """ x.__repr__() <==> repr(x) """
        pass

    def __rmod__(self, y):
        """ x.__rmod__(y) <==> y%x """
        pass

    def __rmul__(self, n):
        """ x.__rmul__(n) <==> n*x """
        pass

    def __sizeof__(self):
        """ S.__sizeof__() -> size of S in memory, in bytes """
        pass

    def __str__(self):
        """ x.__str__() <==> str(x) """
        pass

str

3.【列表】，list   （可以修改）

 1 name = "aslan"
 2 a1 = 18
 3 #创建列表
 4 name_list = ["hsy","aslan","big"]
 5
 6 #索引
 7 print(name_list[1])
 8
 9 #切片
10 print(name_list[0:2])
11
12 #len  大于等于2，小于3
13 print(name_list[2:len(name_list)])
14
15 #循环for
16 for i in name_list:
17     print(i)

列表常用功能

 1 #append追加(括号里可以追加元素)——在列表后边追加一个元素
 2 name_list.append(‘abc‘)
 3 print(name_list)
 4
 5 #count查看列表里有某个元素有几个
 6 print(name_list.count(‘hsy‘))
 7
 8 #interable 可迭代的（只要能通过for循环都是可迭代的）
 9 a2 = [123,456,789]      #批量添加
10 name_list.extend(a2)  #通过extend将一个列表添加到一个列表里
11 print(name_list)      #通过extend成功将a2列表中的元素添加到name_list列表中
12
13 #index 获取指定元素的索引位置（列表里的元素序列号都是从0开始的）
14 print(name_list.index(‘big‘))
15
16 #list 向指定索引位置插入一个元素
17 name_list.insert(1,‘hesiyuan‘)
18 print(name_list)
19
20 #pop 移除列表中最后一个元素并赋值给指定的变量名
21 a3 = name_list.pop()    #将列表最后一个元素移除并赋值给a3
22 print(name_list)
23 print(a3)
24
25 #remove 移除列表中一个指定元素并且每次只能移除一个
26 name_list.remove(‘hesiyuan‘)
27 print(name_list)
28
29 #reverse 反转，将整个列表顺序颠倒，倒序输出
30 name_list.reverse()
31 print(name_list)
32
33 #del 删除指定索引位置
34 print(name_list)
35 del name_list[1:3]  #删除列表中第1、2的元素删除（从1开始到3之前不包括3）
36 print(name_list)

列表其他功能

4.【元组】，tuple     （有序，不可以修改）

 1 #新建元组
 2 name_tuple = (‘hsy‘,‘Aslan‘)
 3 #索引
 4 print(name_tuple[1])
 5
 6 #len     小于等于2，小于3
 7 print(name_tuple[len(name_tuple)-1])    #输出列表中第三个元素，由于没有第三个所以减一
 8
 9 #切片
10 print(name_tuple[0:1])
11
12 #for    ps:(不要忘记for语句结束要有引号结尾)
13 for i in name_tuple:
14     print(i)
15
16 #删除
17 #del name_tuple[0]  不支持

元组常用功能

1 #count  计算元素出现个数
2 print(name_tuple.count(‘hsy‘))
3
4 #index  获取指定元素的索引位置
5 print(name_tuple.index(‘hsy‘))

元组其他功能

5.【字典】 info

 1 #新建字典
 2 #字典的每一个元素就是 ‘键 值 对’
 3 user_info = {
 4     "name":"hsy",
 5     "age" : 18,
 6     "gender": ‘M‘
 7 }
 8 #索引
 9 print(user_info[‘name‘])
10 print(user_info[‘age‘])
11
12 #循环for  ps:for循环语句结束之后切记要有冒号
13 for i in user_info:        #在字典里for循环默认只输出key
14     print(i)

字典常用功能

 1 #获取所有的key
 2 print(user_info.keys())
 3
 4 #获取所有的值
 5 print(user_info.values())
 6
 7 #获取所有的 键 值 对
 8 print(user_info.items())
 9
10 #for
11 for i in user_info.keys():
12     print(i)
13 for i in user_info.values():
14     print(i)
15 for i in user_info.items():
16     print(i)
17
18 #update 更新字典
19 print(user_info)
20 test = {
21     "a1":123,
22     "a2":456
23 }
24 user_info.update(test)
25 print(user_info)
26
27 #删除指定索引的键值对
28 test = {
29     "a1":123,
30     "a2":456
31 }
32 del test[‘a1‘]
33 print(test)

字典其他功能

剖析讲解：字典是无序的

1 user_info = {
2     "name":"hsy",
3     "age" : 18,
4     "gender": ‘M‘
5 }
6 for k,v in user_info.items():
7     print(k)
8     print(v)

剖析讲解二：get

1 #get    根据key获取值，如果key不存在，可以指定一个默认值
2 a1 = user_info.get(‘age‘)
3 print(a1)
4 a1 = user_info.get(‘age111‘,‘对象不存在‘)    #可以设置不存在的值的报错信息
5 print(a1)
6 #ps:索引取值时，key不存在，报错
7 #  get取值时，不会报错