Python path [Article 2]: Python basics, python Article 2

Python path [Article 2]: Python basics, python Article 2
For Python, everything is an object, and objects are created based on classes.

Therefore, the following values are all objects: "zhurui", 22, ['beijing', 'shanghai', 'shenzhen'], and are generated based on different classes.

 

I. Basic data type number (int)

For example, 21, 45, and 56

Each integer has the following functions:

 

1-int 2 converts a string to a number 3 Example: 4 a = "123" 5 print (type (a), a) 6 output result: 7 >>> a = "123" 8 >>> print (type (a), a) 9 <class 'str'> 12310 11 B = int () 12 print (type (B), B) 13 14 output results: 15 >>> B = int (a) 16 >>> print (type (B), B) 17 <class 'int'> 12318 19 num = "0022" 20 v = int (num, base = 16) 21 print (v) 22 23 output results: 24 >>> num = "0022" 25 >>> v = int (num, base = 16) 26 >>> print (v) 27 3428 29-bit_length30 # binary of the current number, expressed with at least n digits 31 age = 2232 v = age. bit_length () 33 print (v) 34 35 output: 36 >>> age = 2237 >>> v = age. bit_length () 38 >>> print (v) 39 5

String (str)

1. name. capitalize () # uppercase letters

Example:

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

 

2. name. casefold () # All the smaller writes, casefold is more awesome, and many unknown small writes

Example:

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

 

3. name. center () # Set the width and center the content

Name. ljust () # Set the width of the variable to the left, and fill the other part with the defined padding.

Name. Fill ust () # Set the width of the variable to the right, and fill the other part with the defined padding.

Name. zfill () # Set the width. The default variable is to the right. Fill the remaining part with the zfill-specific fill character "000 ".

>>> Test = "zhurui" >>> v = test. center (20, "medium") >>> explanation in zhurui in middle of print (v): #20 # * blank unknown filling, one character, optional output results: ############################### ############>> test = "zhurui" >>> v = test. ljust (20, "*") # Place the ljust variable to the left, and fill the other part with *> print (v) zhurui **************######################### ##########>> test = "zhurui" >>> v = test. rjust (20, "*") # The rjust variable is right-aligned, and the other part is filled with *> print (v) *************** zhurui

>>> Test = "zhurui" >>> v = test. zfill (20) # zfill can only be used for 000 filling >>> print (v) 00000000000000 zhurui

 

4. name. count () # search for sub-sequences in strings

>>> 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 () # encode the string into bytes format

6. name. decode ()

 

7. name. endswith ("ui") # judge whether the string ends with the ui

Name. startswith ('ui') # determine whether the string starts with the ui

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

 

8. "Zhu \ tRui". expandtabs (10) # output 'zhu Rui 'to convert \ t to multiple long spaces.

>>> 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) output result: C: \ Python35 \ python3.exe C:/Users/ZR/PycharmProjects/python full stack development/day1/logging. pyusername password emailzhurui 123456 24731701@qq.comzhurui 123456 24731701@qq.comzhurui 123456 24731701@qq.com

9. name. find (A) # find the first one from the start, and obtain the index. If no index is found,-1 is returned.

##> Or> =
#-1 not found
>>> Test = "William" >>> v = test. find ('am') >>> print (v) 5 >>> v = test. find ('T') # find the "t" character in the variable, >>> print (v)-1 ## No, negative 1 is returned

 

10. name. index ('A') # No. An error is returned.

>>> Test = "William" >>> v = test. index ('A') >>> print (v) 5 >>> v = test. index ('8') # Check whether Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: substring not found

 

11. name. format () # format and replace the placeholder in a string with the specified value.

>>> 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 () # format, input value {"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 () # Whether the string contains only letters and numbers

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

 

14. name. isalpha () # whether it is a letter or a Chinese character

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

15. Determine whether the input is a number.

>>> Test = "2" #1, ② >>> v1 = test. isdecimal # judge decimal places> v2 = test. isdigit () >>> v3 = test. isnumeric () # determine Chinese numbers, such as "2"> print (v1, v2, v3) <built-in method isdecimal of str object at 0x00000201FE440AB0> False True

 

16. name. isprintable () # determine whether there are non-printable characters

\ T Tab
\ N line feed
>>> Test = "qepoetewt \ tfdfde" >>> v = test. isprintable () >>> print (v) False >>>> test = "qepoetewtfdfde" >>> v = test. isprintable () >>> print (v) True

 

17. name. isspace () # determine whether all spaces are used

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

 

18. name. istitle () # determine whether it is a title. The first letter must be capitalized.

>>> Test = "Return True if all cased characters in S are uppercase" >>> v1 = test. istitle () >>> print (v1) False >>> v2 = test. title () # capital the first letter of the string >>> print (v2) Return True If All Cased Characters In S Are Uppercase >>>> v3 = v2.istitle () >>> print (v3) true

 

19. ***** name. join () # concatenate each element in the string according to the specified separator (five star key parameter)

>>> Test = "become CEO ">>> print (test) becomes CEO Bai fumei >>> v = '_'. join (test) >>> print (v) outbound _ Ren _ C_E_O _ _ white _ rich _ >>>

 

20. name. islower () # determine whether all are case-insensitive and convert to case-insensitive.

>>> Test = "William" >>> v1 = test. islower () # determine whether all data is in lowercase >>> v2 = test. lower () # convert the variable to lowercase >>> print (v1, v2) false william >>> ################################### >>> test = "William" >>> v1 = test. isupper () # determine whether all data is in uppercase >>> v2 = test. upper () # convert the variable to uppercase >>> print (v1, v2) False WILLIAM

 

21. Remove a specified string and match the string at most.

>>> Test = 'xa '>>> v1 = test. isupper () >>> v = test. lstrip ("xa") >>> print (v) >>> v = test. rstrip ("92 exxxexxa") >>> print (v) >>> v = test. strip ("xa") >>> print (v) #################################### test. lstrip () # test. rstrip () # test. strip () # Remove left and right spaces # v = test. lstrip () # v = test. rstrip () # v = test. strip () # print (v) # print (test) # Remove \ t \ n # v = test. lstrip () # v = test. rstrip () # v = test. strip () # print (v)

 

22. Replace the correspondence

>>> 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 () # split into three parts

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

 

24. name. split () # The number is specified.

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

 

25. segmentation. It can only be set to true or false. whether to retain line breaks.

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

 

26. Start with xxx and end with xx

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

 

27. name. swapcase () # case-insensitive Conversion

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

 

28. name. isidentifier () # letters, numbers, underlines: identifier def class

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

 

29. name. replace () # replace the specified string with the specified string. The replacement function is equivalent to sed.

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