Python之路【第二篇】:Python基础，python第二篇

文章由LinuxBoy分享于2019-04-03 05:04:03热评（503）

Python之路【第二篇】:Python基础，python第二篇

Python基础

对于Python,一切事物都是对象，对象基于类创建

所以，以下这些值都时对象："zhurui"、22、['北京','上海','深圳']，并且是根据不同的类生成的对象。

一、基本数据类型

数字(int)

如：21、45、56

每一个整数都具备如下功能：

 1 - int
 2  将字符串转换为数字
 3 例子：
 4 a = "123"
 5 print(type(a),a)
 6 输出结果：
 7 >>> a = "123"
 8 >>> print(type(a),a)
 9 <class 'str'> 123
10 
11 b = int(a)
12 print(type(b),b)
13 
14 输出结果：
15 >>> b = int(a)
16 >>> print(type(b),b)
17 <class 'int'> 123
18 
19 num = "0022"
20 v = int(num, base=16)
21 print(v)
22 
23 输出结果：
24 >>> num = "0022"
25 >>> v = int(num, base=16)
26 >>> print(v)
27 34
28 
29 - bit_length
30  #当前数字的二进制，至少用n位表示
31 age = 22
32 v = age.bit_length()
33 print(v)
34 
35 输出结果：
36 >>> age = 22
37 >>> v = age.bit_length()
38 >>> print(v)
39 5

字符串(str)

1、name.capitalize() #首字母大写

例子：

>>> test = "zhUrui"
>>> v = test.capitalize()
>>> print(v)
Zhurui

2、name.casefold() #所有变小写，casefold更牛逼，很多未知的对相应变小写

例子：

>>> test = "zhUrui"
>>> v1 = test.casefold()
>>> print(v1)
zhurui
>>> v2 = test.lower()
>>> print(v2)
zhurui

3、name.center() #设置宽度，并将内容居中

　 name.ljust() #设置宽度，变量向左，其他部分用所定义的填充符填充

　 name.rjust() #设置宽度，变量向右，其他部分用所定义的填充符填充

name.zfill() #设置宽度，默认变量向右，其他部分用zfill方法特定的填充符"000" 填充

>>> test = "zhurui"
>>> v = test.center(20,"中")
>>> print(v)
中中中中中中中zhurui中中中中中中中

解释：
#  20   代指总长度
#   *    空白未知填充，一个字符，可有可无

输出结果：
中中中中中中中zhurui中中中中中中中
##########################################
>>> test = "zhurui"
>>> v = test.ljust(20,"*") #ljust 变量靠左，其他部分用*填充
>>> print(v)
zhurui**************

##################################
>>> test = "zhurui"
>>> v = test.rjust(20,"*") #rjust 变量靠右，其他部分用*填充
>>> print(v)
**************zhurui

>>> test = "zhurui"
>>> v = test.zfill(20)  ##zfill只能用于000填充
>>> print(v)
00000000000000zhurui

4、name.count() #去字符串中寻找，寻找子序列的出现次数

>>> test = "Zhuruizhuruiru"
>>> v = test.count('ru')
>>> print(v)
3
>>> v = test.count('z')
>>> print(v)
1

#########################################
>>> test = "Zhuruizhuruiru"
>>> v = test.count('ru', 5, 6)
>>> print(v)
0

5、name.encode() #将字符串编码成bytes格式

6、name.decode()

7、name.endswith("ui") #判断字符串是否以ui结尾

　 name.startswith('ui') #判断字符串是否以ui开始

>>> test = "zhurui"
>>> v = test.endswith('ui')
>>> print(v)
True
>>> v = test.startswith('ui')
>>> print(v)
False

8、"Zhu\tRui".expandtabs(10) #输出‘Zhu Rui’, 将\t转换为多长的空格

>>> test = "Zhu\tRui"
>>> v = test.expandtabs(10)
>>> print(v)
Zhu       Rui

################################
test = "username\tpassword\temail\nzhurui\t123456\t24731701@qq.com\nzhurui\t123456\t24731701@qq.com\nzhurui\t123456\t24731701@qq.com"
v = test.expandtabs(20)
print(v)

输出结果：

C:\Python35\python3.exe C:/Users/ZR/PycharmProjects/python全栈开发/day1/logging.py
username            password            email
zhurui              123456              24731701@qq.com
zhurui              123456              24731701@qq.com
zhurui              123456              24731701@qq.com

9、name.find(A) #从开始往后找，找到第一个之后，获取其位置即索引，找不到返回-1

## > 或 >=
# 未找到 -1
>>> test = "williamwilliam"
>>> v = test.find('am')
>>> print(v)
5
>>> v = test.find('t') #找变量中的"t"字符，
>>> print(v)
-1 ##没有找到，返回负一

10、name.index('a') #找不到，报错

>>> test = "williamwilliam"
>>> v = test.index('a')
>>> print(v)
5
>>> v = test.index('8')  ##找字符串中是否
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: substring not found

11、name.format() #格式化，将一个字符串中的占位符替换为指定的值

>>> test = 'i am {name}, age {a}'
>>> print(test)
i am {name}, age {a}
>>> v = test.format(name='william',a=22)
>>> print(v)
i am william, age 22

>>> test = 'i am {0},age {1}'
>>> print(test)
i am {0},age {1}
>>> v = test.format('william', 22)
>>> print(v)
i am william,age 22

12、name.format_map() #格式化，传入的值{"name": 'william', "a": 22}

>>> test = 'i am {name}, age {a}'
>>> v1 = test.format(name='zhurui',a=22)
>>> v2 = test.format_map({"name":'zhurui', "a": 19})
>>> print(v1)
i am zhurui, age 22
>>> print(v2)
i am zhurui, age 19

13、name.isalnum() #字符串中是否只包含字母和数字

>>> test = "234"
>>> v = test.isalnum()
>>> print(v)
True

14、name.isalpha() #是否是字母，汉字

>>> test = "asfdge242"
>>> v = test.isalpha()
>>> print(v)
False
>>> test = "威廉"
>>> v = test.isalpha()
>>> print(v)
True

15、判断输入的是否是数字

>>> test = "二" # 1 ， ②
>>> v1 = test.isdecimal   ##判断十进制小数
>>> v2 = test.isdigit()
>>> v3 = test.isnumeric()  ##判断汉语的数字，比如 "二"
>>> print(v1,v2,v3)
<built-in method isdecimal of str object at 0x00000201FE440AB0> False True

16、name.isprintable() #判断是否存在不可显示的字符

\t  制表符
\n  换行
>>> test = "qepoetewt\tfdfde"
>>> v = test.isprintable()
>>> print(v)
False
>>> test = "qepoetewtfdfde"
>>> v = test.isprintable()
>>> print(v)
True

17、name.isspace() #判断是否全部是空格

>>> test = ""
>>> v = test.isspace()
>>> print(v)
False
>>> test = " "
>>> v = test.isspace()
>>> print(v)
True

18、name.istitle() #判断是否是标题，其中必须首字母大写

>>> test = "Return True if all cased characters in S are uppercase"
>>> v1 = test.istitle()
>>> print(v1)
False
>>> v2 = test.title()  #将字符串首字母大写
>>> print(v2)
Return True If All Cased Characters In S Are Uppercase
>>> v3= v2.istitle()
>>> print(v3)
True

19、***** name.join() #将字符串中的每一个元素按照指定分隔符进行拼接（五星重点参数）

>>> test = "出任CEO迎娶白富美"
>>> print(test)
出任CEO迎娶白富美
>>> v = '_'.join(test)
>>> print(v)
出_任_C_E_O_迎_娶_白_富_美
>>>

20、name.islower() #判断是否全部是大小写和转换为大小写

>>> test = "William"
>>> v1 =test.islower() #判断是否全都是小写
>>> v2 = test.lower()  #将变量转换为小写
>>> print(v1, v2)
False william
>>>

###################################

>>> test = "William"
>>> v1 =test.isupper() #判断是否全都是大写
>>> v2 = test.upper()  #将变量转换为大写
>>> print(v1, v2)
False WILLIAM

21、移除指定字符串，优先最多匹配

>>> test = 'xa'
>>> v1 =test.isupper()
>>> v = test.lstrip("xa")
>>> print(v)

>>> v = test.rstrip("92exxxexxa")
>>> print(v)

>>> v = test.strip("xa")
>>> print(v)

###################################
# test.lstrip()
# test.rstrip()
# test.strip()
# 去除左右空白
# v = test.lstrip()
# v = test.rstrip()
# v = test.strip()
# print(v)
# print(test)
# 去除\t \n
# v = test.lstrip()
# v = test.rstrip()
# v = test.strip()
# print(v)

22、对应关系替换

>>> test = "aeiou"
>>> test1 = "12345"
>>> v = "asidufkasd;fiuadkf;adfkjalsdjf"
>>> m = str.maketrans("aeiou", "12345")
>>> new_v = v.translate(m)
>>> print(new_v)
1s3d5fk1sd;f351dkf;1dfkj1lsdjf

23、name.partition() #分割为三部分

>>> test = "testegerwerwegwewe"
>>> v = test.partition('s')
>>> print(v)
('te', 's', 'tegerwerwegwewe')
>>> v = test.rpartition('s')
>>> print(v)
('te', 's', 'tegerwerwegwewe')
>>>

24、name.split() #分格为指定个数

>>> test = "sagesgegessress"
>>> v = test.split('s',2)
>>> print(v)
['', 'age', 'gegessress']
>>>

25、分割，只能根据，true, false：是否保留换行

>>> test = "fwerwerdf\frweqnndasfq\fnaqewrwe"
>>> v = test.splitlines(False)
>>> print(v)
['fwerwerdf', 'rweqnndasfq', 'naqewrwe']

26、以xxx开头，以xx结尾

>>> test = "backend 1.2.3.4"
>>> v = test.startswith('a')
>>> print(v)
False
>>> test.endswith('a')
False

27、name.swapcase() #大小写转换

>>> test = "WiiLiAm"
>>> v = test.swapcase()
>>> print(v)
wIIlIaM

28、name.isidentifier() #字母，数字，下划线：标识符 def class

>>> a = "def"
>>> v = a.isidentifier()
>>> print(v)
True

29、name.replace() #将指定字符串替换为指定字符串，替换功能相当于sed

>>> test = "williamwilliamwilliam"
>>> v = test.replace("am", "bbb")
>>> print(v)
willibbbwillibbbwillibbb
>>> v = test.replace("am", "bbb",2)
>>> print(v)
willibbbwillibbbwilliam
>>>

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