Main content: environment configuration, basic data type, basic sequence type
Reference: Getting started with python light speed at station B, python official documentation
python release for windows vscode anconda environment configuration is recommended to use anconda vscode tutorial online Baidu many
>>> bi=True ##Capitalize the first letter otherwise an error will be reported
>>> b1=falseTraceback(most recent call last):
File "<stdin>", line 1,in<module>
NameError: name 'false' is not defined
>>> b1=2>3>>>print(b1)
False
>>>3+36>>>7 /23.5>>>7//2 ####Divide 3>>>7%2 ####Find the remainder
1
>>> s='abc'>>> s
' abc'>>> s="""abc
... def""" #####Triple double quotation marks or three single quotation marks can be used for carriage return and line feed, and one side is used to write a lot of comments
>>> s
' abc\ndef'>>> s='abc\ndef' ######Single quotes need to add newlines
>>> s
' abc\ndef'>>>len(s) ###The length of the string
7>>> s="Haha 123">>> s
' Haha 123'>>>len(s) ###Python can directly recognize Chinese and detect a total of 5 characters
5>>> s1="123">>> t=s+s1 #####String splicing, can be added directly
>>> t
' Haha123123'>>> t=t+12 #####Can not be directly added to the int value
Traceback(most recent call last):
File "<stdin>", line 1,in<module>
TypeError: can only concatenate str(not "int") to str
>>> t=t+str(12) ###Use str to convert an integer to a string
>>> t
' Lol 12312312'>>>isinstance(t,str) ###Used to judge whether it is a certain type
True
You can use built-in functions in Python to convert variable types
int(): Convert a numeric value or string into an integer, and you can specify the base float(): Convert a string into a floating point number. str(): Convert the specified object into a string form, you can specify the code chr(): Convert an integer into a string (a character) corresponding to the code ord(): Convert a string (a Character) into the corresponding code (integer)
list (list), turbo, range are similar to arrays in c language
>>> x=[1,2,3]###list can add elements
>>> type(x)<class'list'>>>> x.append(4) ###Add variables to the list
>>> x
[1,2,3,4]>>> x.append(2)>>> x
[1,2,3,4,2]>>> x[1] is x[4] ###Found that these two are identical
True
>>> t
[' a','d','c']>>> s=[1,2,3]>>> s+t ###List addition
[1,2,3,' a','d','c']>>> x=s+t
>>> x
[1,2,3,' a','d','c']>>> x[3]="xtg" ###List modification The objects in the list are modified, and the original objects will be released inside python
>>> x
[1,2,3,' xtg','d','c']>>> x*2 #####The list is multiplied by a number, the increase of each element of the list
[1,2,3,' xtg','d','c',1,2,3,'xtg','d','c']>>> x=[] ####Set an empty list
>>> x
[]>>> x.append(1) ###You can add elements to it
>>> x
[1]>>> x=[[]]*3 #####The three empty elements created in this way point to the same empty list
>>> x
[[],[],[]]>>> x[1].append(1)###Because it points to the same empty list, the definition will be the same
>>> x
[[1],[1],[1]]>>> x=[[],[],[]] ####The list created in this way is an empty list corresponding to three empty elements
>>> x
[[],[],[]]>>> x[1].append(1)####Adding one does not affect the other
>>> x
[[],[1],[]]
######### slice
>>> x=[1,2,3][1,2,3]>>> y=x[1:3] ####Excluding three and the list retrieved in this way is new and does not match the original one, that is, changing y does not change x.>>> y
[2,3]
>>> x=(1,2,3)>>>x(1,2,3)>>>type(x)<class'tuple'>
##### List can be converted to tuple
>>> x=[1,2,3]>>> x
[1,2,3]>>> x=tuple(x)>>>x(1,2,3)>>>type(x)<class'tuple'>>>> x1=[1,2]>>> x2=[2,3]>>> x3=[4,5]>>> x=(x1,x2,x3)###Create tuple x
>>> x([1,2],[2,3],[4,5])>>> x1=["a","v"] ###x1 is equivalent to re-creating the list without changing x
>>> x([1,2],[2,3],[4,5])>>> x2.append(4) ###But if you add an element to the original list of x2, x will also increase because x references x2
>>> x([1,2],[2,3,4],[4,5])
String creation can use single quotes', double quotes "", triple quotes """ """
>>> s="this is an apple">>> s
' this is an apple'>>>'i'm sam' #####If single quotes are used in the string, you need to add an escape character\,Otherwise it won't recognize
File "<stdin>", line 1'i'm sam'
^
SyntaxError: invalid syntax
>>>' i\'m sam'
" i'm sam
###########\ The backslash does not want to be used as an escape character, you can add a prefix r, or add two\\
>>> s=r'd:\dir\t.txt'
>>> pattern ='%s is %d years old.'>>> pattern
' %s is %d years old.'>>> name ='tom'>>> age =12>>> msg = pattern %(name,age) ######The type of percent sign plus tuple can be used as a format string pattern is(str % tuple)>>> msg
' tom is 12 years old.'>>> pattern ='%10s is %d years old.' #####Ten placeholders
>>> msg =pattern %(name,age)>>> msg
' tom is 12 years old.'
{ : Data type}.format() format brackets are the parameters that need to be added
>>> msg='{:d}+{:d}={:d}'.format(1,12,1+12)>>> msg
'1+12=13'
### Before the colon, you can specify which parameter to display
>>> msg='{1:d}+{0:d}={2:d}'.format(1,12,1+12)>>> msg
'12+1=13'
>>> name,age('tom',12)>>> f'{name} is {age} years old''tom is 12 years old'
The string object is read-only and cannot be changed. If it is changed, a new object must be created
>>> str.capitalize('trr') ####Capitalize the first letter
' Trr'>>> s ='hello, world!'>>>print(s.title()) ##Get a capitalized copy of each word in the string
Hello, World!>>>print(s.upper()) ####Obtain a copy of the string when it is capitalized
HELLO, WORLD!>>>print(s.find('or')) #Find the location of the substring from the string,Return if the difference is not found-18>>>print(s.find('t'))-1>>> s
' hello, world!'>>> s.replace('hello','hi')###Replacement string
' hi, world!'>>> text='1,2,3,4,5'>>> text
'1,2,3,4,5'>>> text.split(",") ####Separate the separator, for example, it is often used when reading text
['1','2','3','4','5']>>> text[2]'2'>>> text[2]='c' ########The string is read-only and cannot be rewritten,Cannot be modified by removing the subscript
Traceback(most recent call last):
File "<stdin>", line 1,in<module>
TypeError:'str' object does not support item assignment
>>> text[2:7] ###If you want to modify the way to remove the subscript, you can modify the string to a list
'2,3,4'>>> lt=list(text)>>> lt
['1',',','2',',','3',',','4',',','5']>>> lt[0]='a'>>> lt
[' a',',','2',',','3',',','4',',','5']>>> s='' ####If you want to change the list back to a string, which is troublesome, you can create an empty string first, add it at a time, and use a loop.
>>> s += lt[0]>>> s
' a'>>> s += lt[1]>>> s
' a,'>>> s += lt[2]>>> s
' a,2'
if while for
score =int(input('hh input score: '))if score >=90:
grade='A'
elif score>=80:
grade='B'
elif score>=70:
grade='C'else:
grade='D'print(f'your grade is {grade}.') ###f string
i=1
sum=0while i<=100:
sum +=i
i +=1print(sum)
scores=[90,80,20,40,33,24,80]for scores in scores:if scores >=60:print("pass")else:print("nopass")
####################################
$ python python/python02/python02.py
pass
pass
nopass
nopass
nopass
nopass
pass
for i inrange(10):print(i)
$ python python/python02/python02.py
0123456789
########### You can take out the subscript, then for a list, you can use range to take out all the values in the following table
score=[10,20,34,84,92,100]for i inrange(len(score)):print(score[i])
$ python python/python02/python02.py
1020348492100
######## How can I get both the subscript and the value
score=[10,20,34,84,92,100]for score inenumerate(score):print(score)
$ python python/python02/python02.py(0,10)(1,20)(2,34)(3,84)(4,92)(5,100)
############ Tuples are replaced by values
>>> x=(1,2)>>> idx,score=x
score=[10,20,34,84,92,100]for idx,value inenumerate(score):print(idx,value)
$ python python/python02/python02.py
0101202343844925100
######### I want to output the contents of the two lists zip package the two lists
score=[10,20,34,84,92,100]
names=['sam','tom','hhh','type','mary','lili']for score,names inzip(score,names):print(score,names)
$ python python/python02/python02.py
10 sam
20 tom
34 hhh
84 type
92 mary
100 lili
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