python函数（一）调用函数

　　在python中内置了很多函数或者类，比如：int，str，list，tuple，等。当然也可以自建函数，这个放在后文讨论。原理如下：

　　

　　其实python中的类和方法非常非常多，这里只是以点带面，提供一个学习的方法。

　　（一）int

使用举例

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

age = -19　　　　　　　　　　　　　　　　　  #其实是执行了一个__init__的过程。
print (type(age))　　　　　　　　　　　　　 #打印age的类型
age = int(age)
re =  age.__float__()                   #将age的类型变成浮点类型，注，本来是int类型。
print(type(re))                         #打印re的类型
reslutd = age.__abs__()                 #绝对值.(-19)=19。    <===>...reslutd=abs(age)
reslut = reslutd.__divmod__(3)          #divmod得出商和余数，19/4。在写扉页的时候会用到。<===>...reslutd=divmod(age)
reslut_fan = reslutd.__rdivmod__(4)     #反向求商和余数。4/19
print(reslutd,reslut_fan,reslut)

#结果
'''
<class 'int'>
<class 'float'>
19 (0, 4) (6, 1)
'''

　　按住Ctrl，点击int，可以在builtins模块中看到int成员，其中int成员里大部分都是带下划线的，这一类的功能大多是通过内置方法就可以直接执行（例子参考上面abs,divmod和下文中add），请看：

def __abs__(self, *args, **kwargs): # real signature unknown
    """ abs(self) """
    pass
#取绝对值

def __add__(self, *args, **kwargs): # real signature unknown
    """ Return self+value. """
    pass
#相加，print(1+1)其实就是调用了“int”中内置的__add__这个函数，所以可以直接执行。但过程依然是：创建对象，调用方法，得到结果。

def __and__(self, *args, **kwargs): # real signature unknown
    """ Return self&value. """
    pass
#融合
def __bool__(self, *args, **kwargs): # real signature unknown
    """ self != 0 """
    pass
#变成波尔类型

def __pow__(self, *args, **kwargs): # real signature unknown
    """ Return pow(self, value, mod). """
    pass
#取指数

....

def bit_length(self): # real signature unknown; restored from __doc__
    """
    int.bit_length() -> int

    Number of bits necessary to represent self in binary.
    >>> bin(37)
    '0b100101'
    >>> (37).bit_length()
    6
    """
    return 0
#返回用最少多少位可以表示当前数字
#举例：
a= 59
result = a.bit_length()
print(result)
#结果
6

int成员

（二）str

先来个例题

#字符串。str如‘张洪震’‘zhang’。举例：
name = 'zhang'
name = str('zhang')                          #str执行时其本质是执行的.__init__方法.按住Ctrl，点击“str” ，查看有哪些成员
print(type(name))                            #tpye.快速获取类
print(dir(name))                             #dir.快速获取这个类里面有哪些成员
a = name.__contains__('ang')                 #a<=>b,a和b其实是一样的。
b = 'zh' in name
print(a,b)

#结果：
'''
<class 'str'>
['__add__', '__class__', '__contains__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__gt__', '__hash__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'capitalize', 'casefold', 'center', 'count', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'format_map', 'index', 'isalnum', 'isalpha', 'isdecimal', 'isdigit', 'isidentifier', 'islower', 'isnumeric', 'isprintable', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'maketrans', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']
True True

来看下其他的成员：

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

a = 'abc'
def capitalize(self): # real signature unknown; restored from __doc__
        """
        S.capitalize() -> str
       #让第一个字母大写
        """
        return ""
a1 = a.capitalize()
print(a1)
#结果
#Abc

def center(self, width, fillchar=None): # real signature unknown; restored from __doc__
        #width宽度；fillchar=None，填充字符，默认为空格
        """
        S.center(width[, fillchar]) -> str
        Return S centered in a string of length width. Padding is
        done using the specified fill character (default is a space默认为空格)
        """
        return ""
a2 = a.center(10)                           #让a这个字符串宽度为10.且abc位于中央。
print(a2)
#   abc
a3 = a.center(10,'@')　　　　　　　　　　　　　　#以@为填充符。
print(a3)
#@@@abc@@@@

def count(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
        """
        #统计子序列出现的次数。
        #sub附属的，起始位置，结束为止
        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
a4 = a.count('a',0,2)                     #计算从0-2之间有几个a。
print(a4)
#

def encode(self, encoding='utf-8', errors='strict'): # real signature unknown; restored from __doc__
    """
    #转码，encoding是编码方式；默认转成utf-8。errors是错误处理方式。
    S.encode(encoding='utf-8', errors='strict') -> bytes
    """
    return b""                            #返回为b""，就是以b开头。
A = '张洪震'
a5 = A.encode('gbk',errors='ignore')　　　 #转成gbk编码，忽略错误。注：其实内部还是从utf-8转为Unicode，再从Unicode转为gbk。
print(a5)
#b'\xd5\xc5\xba\xe9\xd5\xf0'

def endswith(self, suffix, start=None, end=None): # real signature unknown; restored from __doc__
    """
    S.endswith(suffix[, start[, end]]) -> bool
    #suffix后缀，
    suffix can also be a tuple of strings to try.#后缀也可以是一个元组。
    """
    return False　　　　　　　　　　　　　　　 #返回正误
a6 = a.endswith('c',0,3)                   #这里注意一下，是0<=suffix position.<3，
#a6 = a.endswith('c',0,2)，这样写会报错。
print(a6)
#True

def startswith(self, prefix, start=None, end=None): # real signature unknown; restored from __doc__
        """
        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.
        判断是否是以“。。”开头，可以指定开头和结尾的位置，
        """
        return False

def expandtabs(self, tabsize=8): # real signature unknown; restored from __doc__
        """
        S.expandtabs(tabsize=8) -> str
        Return a copy#副本of S where all tab characters are expanded using spaces.
        If tabsize is not given, a tab size of 8 characters is assumed.
        #返回一个用空格代替tab键的副本。
        """
        return ""
B = 'zhan   g'
b7 = B.expandtabs()
print(b7)
#zhan   g

def find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
        """
        #查找出sub所在的位置。
        S.find(sub[, start[, end]]) -> int
        Return -1 on failure.#如果失败的话返回-1.
        """
        return 0
a8 =a.find('c',0,3)                         #在0-2的位置找c。
a9 =a.index('b')                            #index和find都是找，index找不到的话会直接报错。
print(a8,a9)
#2 1

def format(*args, **kwargs): # known special case of str.format
        """
        S.format(*args, **kwargs) -> str
        Return a formatted version of S, using substitutions from args and kwargs.
        返回一个格式化的字符串，用替换的来自于传参。
        The substitutions are identified by braces ('{' and '}').
        被替换的东西用{}来定义
        """
        pass
C ='zhen,{0},{1}'
a10 = C.format('是四个字母','对')            #传参为“是四个字母”
print(a10)
#zhen,是四个字母,对
D ='zhen,{dd},{ddd}'
a10 = D.format(dd='是四个字母',ddd='对')     #做一个动态对应
print(a10)
#zhen,是四个字母,对

#以is开头的大都是判断，举一个例子
def isalnum(self): 　　　　　　　　　　　　　　# 判断是否是文字数字
        return False

def join(self, iterable): # real signature unknown; restored from __doc__
        """
        #主要用来做拼接
        S.join(iterable) -> str
        Return a string which is the concatenation of the strings in the
        iterable.
        The separator between elements is S.元素之间的分隔符是S.。
        """
        return ""
E=['ni hao','zhang','chi le ma']          #定义一个列表
a11= ",".join(E)                          #让“E”中的字符串以“，”为分割符相连。
print(a11)
#ni hao,zhang,chi le ma

def ljust(self, width, fillchar=None): # real signature unknown; restored from __doc__
    """
    S.ljust(width[, fillchar]) -> str
    左对齐。参数为宽度，填充字段.默认为空
    """
    return ""

def rjust(self, width, fillchar=None): # real signature unknown; restored from __doc__
    """
    S.rjust(width[, fillchar]) -> str
    右对齐。参数为宽度，填充字段，默认为空
    """
    return ""
F = 'abc'
a12=F.ljust(7,'#')　　　　　　　　　　　　　　#让F的宽度为7个字符，如果不够7个，那么在字符串的右边填充上“#”把字符串“挤”至左对齐。
print(a12)
a13=F.rjust(6,'$')　　　　　　　　　　　　　　#让F的宽度为6个字符，如果不够6个，那么在字符串的左边填充上“#”把字符串“挤”至右对齐。
print(a13)
#结果
'''
abc####
$$$abc
'''

def lower(self): # real signature unknown; restored from __doc__
        """
        S.lower() -> str
         Return a copy of the string S converted to lowercase.
       返回一个字符串的小写副本。
        """
        return ""
def upper(self): # real signature unknown; restored from __doc__
        """
        S.upper() -> str
        大写
        Return a copy of S converted to uppercase.
        """
        return ""

def strip(self, chars=None): # real signature unknown; restored from __doc__
        """
        S.strip([chars]) -> str
        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.
        删除开头和结尾空格，如果给定字符或不是空的，那么删除给定字符
        """
        return ""
def lstrip(self, chars=None): # real signature unknown; restored from __doc__
        """
        S.lstrip([chars]) -> str
        Return a copy of the string S with leading whitespace removed.
        If chars is given and not None, remove characters in chars instead.
        返回一个去掉字符串的开头空格的副本
        如果给定字符而不是空的，则删除给定字符。
        """
        return ""
a14=a.lstrip('a')
print(a14)
def rstrip(self, chars=None): # real signature unknown; restored from __doc__
        """
        S.rstrip([chars]) -> str
        Return a copy of the string S with trailing whitespace removed.
        If chars is given and not None, remove characters in chars instead.
        返回一个去掉字符串的结尾空格的副本
        如果给定字符而不是空的，则删除给定字符。
        """
        return ""
a15=a.rstrip('c')
print(a15)

def partition(self, sep): # real signature unknown; restored from __doc__
        """
        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.
        在字符串中搜索分隔符，并返回它前面的部分、分隔符本身和后面的部分。如果找不到分隔符，返回s和两个空字符串。
        """
        pass
a16= a.partition('b')　　　　　　　　　　　　#以b为分隔符
print(a16)
#('a', 'b', 'c')
a17= a.partition('d')　　　　　　　　　　　　#以d为分割符
print(a17)
#('abc', '', '')

def replace(self, old, new, count=None): # real signature unknown; restored from __doc__
        """
        S.replace(old, new[, count]) -> str
        old replaced by new.  If the optional argument count is
        given, only the first count occurrences are replaced.
        """
        return ""
h='aaaaaaa'
h1= h.replace('a','b',3)　　　　　　　　　　#用b替换a,个数为3
h2=h.replace('a','',2)
print(h1,h2)
#bbbaaaa 99aaaaa

def split(self, sep=None, maxsplit=-1): # real signature unknown; restored from __doc__
        """
        S.split(sep=None, maxsplit=-1) -> list of strings
        分割。
        """
i='zhang hong z hen'
i1=i.split('h',2)　　　　　　　　　　　　　　#指定h为分隔符，i中有3个h，指定最大为2个，所以，只有两个作为分割符了
i2=i.split()　　　　　　　　　　　　　　　　　#没有指定，则以空格为分割符并删除空格
print(i1,i2)
#['z', 'ang ', 'ong z hen'] ['zhang', 'hong', 'z', 'hen']

def swapcase(self): # real signature unknown; restored from __doc__
        """
        S.swapcase() -> str
        Return a copy of S with uppercase characters converted to lowercase
        and vice versa.
        如果是大写，那么给它换成小写，反之亦然。
        """
        return ""

def title(self): # real signature unknown; restored from __doc__
        """
        S.title() -> str

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

str其他成员

　　

　　 通过上面可以看出其实python的解释很清晰简洁，真的难懂的话可以通过翻译软件翻译出来，一般情况下是可以看懂的。

（三）list列表

如：['zhang']、[11,'hong','zhen']

class list(object):
    """
    list() -> new empty list
    list(iterable) -> new list initialized from iterable's items
    """
    def append(self, p_object): # real signature unknown; restored from __doc__
        """ L.append(object) -> None -- append object to end """　　　　　　　　#从列表末尾加入元素
        pass

    def clear(self): # real signature unknown; restored from __doc__
        """ L.clear() -> None -- remove all items from L """　　　　　　　　 　　#清除所有
        pass

    def copy(self): # real signature unknown; restored from __doc__
        """ L.copy() -> list -- a shallow copy of L """　　　　　　　　　　　　　　#浅拷贝
        return []

    def count(self, value): # real signature unknown; restored from __doc__
        """ L.count(value) -> integer -- return number of occurrences of value """
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　#计数
        return 0

    def extend(self, iterable): # real signature unknown; restored from __doc__
        """ L.extend(iterable) -> None -- extend list by appending elements from the iterable """　　
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　  　#扩展，将新列表元素加到老列表中

        pass　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

    def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
        """
        L.index(value, [start, [stop]]) -> integer -- return first index of value.
        Raises ValueError if the value is not present.　　　　　　　　　　　　　 　#下标，也就是索引号
        """
        return 0

    def insert(self, index, p_object): # real signature unknown; restored from __doc__
        """ L.insert(index, object) -- insert object before index """　　　　　　#指定位置插入元素
        pass

    def pop(self, index=None): # real signature unknown; restored from __doc__
        """
        L.pop([index]) -> item -- remove and return item at index (default last).
        Raises IndexError if list is empty or index is out of range.　　　　　　　#移除，参数为指定位置
        """
        pass

    def remove(self, value): # real signature unknown; restored from __doc__
        """
        L.remove(value) -> None -- remove first occurrence of value.
        Raises ValueError if the value is not present.　　　　　　　　　　　　　　 　#移除，参数为指定的值
        """
        pass

    def reverse(self): # real signature unknown; restored from __doc__
        """ L.reverse() -- reverse *IN PLACE* """　　　　　　　　　　　　　　　　　 　#反转，即倒序。
        pass

    def sort(self, key=None, reverse=False): # real signature unknown; restored from __doc__
        """ L.sort(key=None, reverse=False) -> None -- stable sort *IN PLACE* """ #排序。
        pass

list成员

（四）tuple元组

如：（11,22,）('zhang',[11,22,33],)

class tuple(object):
    """
    tuple() -> empty tuple
    tuple(iterable) -> tuple initialized from iterable's items

    If the argument is a tuple, the return value is the same object.
    """
    def count(self, value): # real signature unknown; restored from __doc__
        """ T.count(value) -> integer -- return number of occurrences of value """#计数
        return 0

    def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
        """
        T.index(value, [start, [stop]]) -> integer -- return first index of value.#返回一个索引
        Raises ValueError if the value is not present.
        """
        return 0
　　　　#例：
　　　　a=(('zhang'),[11,22,33],)
　　　　re=a.index('zhang')
　　　　print(type(a),re)

　　　　#<class 'tuple'> 0

tuple成员

（五）dict字典

如：{'张':'shuai','host':'Cmelo.com','123':'abc'}

使用：

name1=[11,22,33,44,55,66,77,88,99]
name2=[1,2,3,4,5,6,7,8,9]
dict['k1']=name1 #<=>dic=dict(k1=name1)
dict['k2']=name2 #<=>dic2=dict(k2=name2)

dict

dd={'张':'shuai','host':'Cmelo.com','':'abc'}

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. 如果key在D中就是key，否则就是设置的d。d默认是空"""
        pass
    #例
    dd={'张':'shuai','host':'Cmelo.com','':'abc'}
    kk= dd.get('li','sorry,meiyouzhaodao')
    print(kk)
    #sorry,meiyouzhaodao

    def items(self): # real signature unknown; restored from __doc__
        """ D.items() -> a set-like object providing a view on D's items 输出所有的字典对儿"""
        pass

    def keys(self): # real signature unknown; restored from __doc__
        """ D.keys() -> a set-like object providing a view on D's keys 输出所有的key值"""
        pass
    def values(self): # real signature unknown; restored from __doc__
        """ D.values() -> an object providing a view on D's values 输出所有的value值。"""
        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.给定k值，删除相应的value
        If key is not found, d is returned if given, otherwise KeyError is raised如果key没有找到，如果给了d的话d会输出。否则，报错,
        """
        pass
    #例：
    dd={'张':'shuai','host':'Cmelo.com','':'abc'}
    aa= dd.pop('li','sorry,meiyouzhaodao')
    bb=dd.pop()
    print(aa,bb)
    #sorry,meiyouzhaodao
    #bb=dd.pop()
    #TypeError: pop expected at least 1 arguments, got 0

    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.                            #随机删除一个对儿，如果参数是空的话会报错
        """
        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   给设置一个默认值"""
        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 __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

dict成员