full stack development tutorial

the task is waiting to be executedThe queue is a built-in lock, so it is safe for other applications to call it.When it comes to manual locking, it is unsafe. Commonly used is the message middlewareGalena with no return valueClose and join paired useImport timefrom multiprocessing Import pooldef Wahaha (i): time.sleep (1) print (' * ' * i) if __name__ = = ' __main__ ': p = Pool (5) # The recommended number is CPU cores +1 for I in range (5): P.apply_async (Func=wahaha

1. Formatted output uses string concatenation to form a template: This leads to formatted output: (Personal business Card making) use of formatted output: The% placeholder S is the character, and D represents the number%s%d%r??? The first format: (Must be one-to-one) the second format: (no one by one correspondence) Note: Formatted output, in the formatted output, the simple representation of% need to use percent of 2.while......else ... (The specific scene will be used) when the while loop is n

#max, Min,zippeople1={ 'Age1': 123,'Age2': 56,'Age3': 554,'Age4': 67,'Age5': 234,'Age6': 34,'Age7': 45} #取出key值可以知道对应值 with zipPrint(List (max (Zip (people1.values (), People1.keys () )))Print(list (Zip (People1.values (), People1.keys ()))) Max,min parameter (the object that can be used, the key method (typically a lambda expression)) people=[ {'name':'Lu',' Age': 123}, {'name':'Jia',' Age': 134}, {'name':'Cheng',' Age': 143}, {'name':'Lu',' Age': 112}]Print(Max (people,key=Lambd

#读1 f=open ('d:\\k.py', encoding='UTF8') 2 print (F.readline ()) 3 print (F.readline ()) 4 print (F.readline ()) #读一行readline5print (f.readable ()) #读全部, converting each line to a list string 6print (F.readlines ())7 f.close ()#写文件F=open ( ' li Chen ','w') f.write ('1244\ n43564\ngergre\nghhrt\n') f.writelines (['fsdgfwsdg', ' 3242 ']) # A String f.close () than required#追加F=open (' li Chen ','a') #a mode append f.write ( ' FDHDH ' ) f.write ('hgfbf') f.close ()#总结加其它#打开文件模式R

#!/usr/bin/env Python can declare the Python interpreter used by Liunx (unique)Coding#-*-Coding:utf-8-*-Python2 have Chinese language to add the code in the header file Plus, Python3 do not use, the default is Utf-8 (also can be written UTF8)Python syntax#变量名1. Letters2. Digital3. Underline#永远等待 until the user enters a value, n generation refers to the value entered by the userN=input (' Please enter user name: ')#条件语句　If condition:Statement blockElif Conditions:Statement blockElseStatement bloc

not changed, to add the function of timingNested functions:def foo (): Print ('in thefoo') def Bar (): Print ('in thebar') bar () foo ()Combine the above three implementations of adorners:Import TimedefTimer (func):#timer (Text1) func=text1 adorner function defWrapper (*args,**Kwargs): Start_time=time.time () func ()#Run Text1Stop_time =time.time ()Print('The Fun run time is %s'% (stop_time-start_time)) returnWrapper@timer#Text1 = Timer (Text1) This step is to pass the Tex

Print("Exit Loop")#Output "Exit loop" after an even-numbered Onej = 1 A while1:#the cycle condition of 1 must be set - Print(j)#Output 1~10 -J + = 1 the ifJ > 10:#when I is greater than 10 o'clock jump out of the loop - Break - Else: - Print("Exit Loop")#does not output this statement because it is a break exitThe cycle of death, the inability to exit the loop, the damage to the computer is large:1 while Ture: 2 Print (" dead Loop ") # execution of the statement

receives the value after next.4. Concurrent runsRequirements Analysis: Two functions, one function calls another function, and then saves the state in such a way.defChibaozi (name):Print('I'm starting to eat buns.') while1: Baozi=yield Print('This is the bun I ate.%s'%Baozi)defZuo (): S1=chibaozi ('Yehaibin') s1.__next__() forIinchRange (10): S1.send ('Lvelvelve') Zuo ()When running Zuo, each cycle, Chibaozi will do one action, and then save the state, which is yield. #其实我现在还不太懂,

, iterate, using the next method continuously until an exception is obtained, and the iterator ends. 3. Why Use iteratorsThe benefit of iterators: The iterator makes the data into memory for each time it is next. If it is a list, a large amount of memory to go into memory, the data is more likely to cause the crashLike what:The sum of the list (range (1000000)) is calculated and the data needs to be put into memory at once.In the case of iterators, using one data at a time, the first 1+2, the se

ID (variable): Returns a memory addressK1 is K2: Determine if their memory address is consistentK1 = = K2: Determine if their values are consistentSmall Data pools:-5-256STR: the same stringSTR * INT: Their length is not more than 20, the memory is consistentTheir memory addresses are all the same.CodingUse UTF-8 or GBK encoding during transferIn memory: The encoding is Unicode during our program's RunIn a program, a string can be encoded into a bytes type of datacode encode ()Grammar:Variable

form4. Various methods4.1 f.encoding ()What encoding to open when the file is opened4.2 F.flush ()Changes to the file in memory, written to the hard disk4.3 F.tell ()Displays the location where the cursor is currently located. #除了read是显示光标所在字符的位置, the rest is the display character position4.4f.seek ()There are three different modes4.4.1 0F.seek (4.0) The first way, from the beginning of the file, to move four bytes4.4.2 1F.seek (3.1), moving three bytes from the relative position of the cursor4

cursor is showing. When you write to or manipulate the file, it is done at the end. So if you want to do the truncation operation. Remember it. To nudge the cursor first. Move to the position you want to truncate. Then truncate about truncate (n), if given N. Is truncated from the beginning, and if n is not given, it is truncated from the current position. Subsequent content will be deleted.Another way to open a file:　　 with open ("Doll", mode= "R", encoding= "Utf-8") as F1:This does not need t

Study_recordCREATE TABLE' Study_record ' (' ID ')int( One) not NULL,` Day`int( One) not NULL, ' status 'Char( +) not NULL, ' stu_id 'int( One) not NULL,PRIMARY KEY(' id '),KEY' fk_class_key ' (' stu_id '),CONSTRAINT' Fk_student_key 'FOREIGN KEY(' stu_id ')REFERENCES' Student1 ' (' id '))Show create table Study_record; View table creation RecordCreate a tableCreate B TableSELECT * FROM A inner join B on a.a=b.b; or select a.*,b.* from A, where a.a=b.b;SELECT * from A LEFT join B on a.a=b.b; diff

, there is no such restriction when used, the left side of the point can be a package, a module, a function, a class (they can all call their own properties in the way of a point).3. Compare the application scenarios for import item and from item import name:If we want to use name directly then we must use the latter.4.importImport glance.db.modelsglance.db.models.register_models (' MySQL ')5.__init__.py file:Either way, the first time the package is imported or any other part of the package, th

HTML: Defines which elements of a Web page areCSS: Defines how page elements are renderedJS: Defines how page elements interact with the userHTML (hypertext Markup Language) Hypertext Markup Languageis a markup languageMarkup language is a set of tag tagsHTML uses tag tags to describe web pagesCSS (cascading style Sheets) cascading style SheetsStyle defines how HTML elements are displayedStyle sheets can be built into HTML files, but professional practice is to store them independentlyJS (JavaSc

>123123TD> TR> TR> TD>AlexTD> TD>123123TD> TR> TR> TDcolspan=2>Watchmakers: XXXTD> TR> Table>Body>HTML>Tables are created using tags You cannot use the In addition to the Across rows and across columns, the cross-row and cross-column display can only be set in TD or TH, because this is the operation of the cell, and the TD and th are the cells.TR is not a cell, it is an entire row.There are also cell spacing, margins, and so o

Variable:Variables are stored in order to store some intermediate results in the process of program operation, in order to facilitate later invocation.Cases:Print ("Hello world!")Print ("Alon")Print ("alon_x")Name = ("alon_x")X=3Y=4Z=x*yPrint ("X*y", Z)Print ("z=", Z)The code format must be aligned, or it will be an error. indentationerror:unexpected indent ("Hi, man, your file is not in the right format, it may be the tab and space is not aligned, you need to check the tab and the Space ")Defin

word, and the Kerning method is as follows:word-spacing:30px;And this word-spacing to Chinese is not effective oh. To set the Chinese spacing, use letter-spacing to set it up OHtext-shadow:2px 2px #ff0000;This can be used to set the shadow of the text, note that the parameters are separated by a space, not separated by semicolons.{line-height:200%}Line-height can be used to set the row height.Of course there are many other properties that set text formatting that can be viewed in the manual.In

container div, which is container, then the width of the container is 1200px, the height is 800px, the background is gray, if the height is not specified, then it will be based on the contents of the height.This container contains a total of four blocks, one is content, used as the main display, one is the head, header, used to put the first title of the page.A left title bar, the ID of this title bar is Menu-left, the width of this block is 100, plus the content width 1000, less than the width

In CSS, all HTML elements can be viewed as a box.So in the design and layout, the most commonly used, that is, to define the margin of the box is marginDefining the inner margin of the box is padding.The width of the element's content is set by the wide property, so what is the total width of the element in the HTML page?is width + padding-left + padding-right + border-left-width + border-right-width This is the total width of the entire HTML page that the element occupies.For borders, we can us