python foundation udacity

set of content in memory, and any modification to one of the two variables in this process will not affect the other variables . Let's try it out here.Looking at the results of the above implementation, this time we will not be affected by the list of copies, regardless of whether we operate directly on the list or on other data structures nested inside the list. Let's look at the state of these variables in memory:Looking at the above, we know the principle of deep copy. In fact, deep copy is

a corresponding memory object is an inverse sequence.Serialization persistence of memory dataJson.dumps (data) for serializationJson.loads (F.read ()) for data serializationJson.dump (data) for serializationJson.load (F.read ()) for data serialization5.1 JSON serializationImport JSONdata = {' name ': ' Zs ', ' Age ': 26}f = open (' Json.txt ', ' W ', encoding= ' utf-8 ')F.write (Json.dumps (data))F.close ()Import JSONdata = {' name ': ' Zs ', ' age ': +, ' sex ': ' Men '}f = open (' Json.txt ',

executable.else is optional, when the condition is set, the statement skips and executes when the condition is not established.Age_oldboy = 56guess_age = Int (input (' age ')) #输入自己猜测年龄if guess_age = = Age_oldboy: #判断输入年龄是否相等. Print (' yes,you got it ') #条件成立时输出else:p rint (' No, it is wrong ') #不成立时输出When judging multiple conditions, a single if else does not meet the requirements. This can be resolved as follows.If judgment condition 1: EXECUTE statement 1......elif judgment Condition

this way, Python is not as efficient as serial (no large switching) for computationally intensive tasks, but there is a significant increase in efficiency for IO-intensive tasks.Io Intensive cases:Import threadingImport timedef foo (n):Time.sleep (N)Print ("foo....%s"% n)Print (Threading.activecount ())def bar (N):Time.sleep (N)Print ("bar......%s"% n)S=time.time ()T1=threading. Thread (target=foo,args= (2,))#t1. Setdaemon (True)T1.start ()T2=threadi

from the real work2: Code easier to organize, clearer, complex tasks easier to implement;3: No doubt, more secure, not due to some small negligence to make the program accidentally collapsed;Iii. when to use exception handlingTry...except should be used sparingly, because it is an exception-handling logic that you attach to your program, which is not related to your main work.This kind of things add more, will lead to your code readability is poor, only in some abnormal unpredictable circumstan

(1) CPython: for the widest(2) PyPy: Using JIT technology, fast execution speed(3) Jython"V" Learning recommendations(1) 1991, Python was born(2) python2.7,2010 July 3Note: Support to 2020(3) python3.5, September 13, 2015Note: Python 3.4+ is recommended"VI" Python 2.x and Python 3.x(1) Print usage(2) library names from

returned to none.>>>defPrinthello ():Print 'Hello' #no return statement>>>defTest ():Print 'This is printed' return #return to the end of the statement, indicating that the function call executes to this end Print ' This isn't'>>> x =Test () this isPrinted>>> >>>defAdd (A, B):#the params parameter can be 0, one, or multiple returnA +b>>>PrintAdd ()3>>>Second, the use of functionsAfter defining a function, you can use the function, but in

) return instance[cls] return _singleton@singletonclass People(object): def __init__(self,name, age): self.name=name self.age=age def add(self): passs = People('alex',23)s1 = People('kate',28)print(s==s1) # True28. What is the difference between a single case using an adorner and a single case using another method? Code reuse 29. Handwritten regular email addresspattern = '[1-9a-z][emailprotected](qq|126|163|gmail|foxmail|yahoo)\.com'import r

, jump out of this cycle, the next cyclei = 1 while I : if i==7 : i+=1 continue Print(i) i+=1The break keywordi = 1 while I : if i==7 : break print(i) I+=1only executes to 7, interrupts the loop, and the subsequent array no longer prints the output .Related Work Problems1.using while loop input 1 2 3 4 5 6 8 9# 1 2 3 4 5 6 8 9n = 1 while n : if n! = 7: Print (n) Else : print () + = 1 loop output 1-10, ex

variable __name__ will derive different values depending on how the python file is loadedPython files are imported as modules: __name__= module name or file namePython file executed: __name__= ' __main__ 'When we use Python to write a software, there should be only one main program that contains a lot of top-level code (that is, code without indentation).The Python