practice of programming

. If operation A is performed before action B and action B is performed before Operation C, then operation a must be performed before Operation C.The following is an English description of happens-before,the Happens-before relation defines when data races take place. An unlock in a monitor happens-before every subsequent lock on the that monitor. A write to a volatile field happens-before every subsequent read of the that field. A call to start () on a thre

cost is $. " ) else : print ( " your admission cost is $. ") Python does not require the IF-ELIF structure to have an else code block, else is an all-encompassing statement, as long as the non-satisfied will execute else under the statement, may cause invalid or even malicious data, if you know the final test conditions, you should consider the elif instead of else! No matter if-n a elif-else, as long as one satisfies, it will only execute the condition that evaluates to true and will n

[_outputstream write:buff Maxlength:strlen ((const char *) buff) +1] is written as data method.The ⑥ and ⑦ line code [self close] calls the Close method closed, and the Close method code is as follows:-(void) Close{[_outputstream close];[ _outputstream Removefromrunloop:[nsrunloop Currentrunloop]formode:nsdefaultrunloopmode]; [_outputstream Setdelegate:nil]; [_inputstream Close]; [_inputstream Removefromrunloop:[nsrunloop Currentrunloop]formode:nsdefaultrunloopmode]; [_inputstream Setdelegate:n

Ownership of the stateThe object encapsulates its state, owning the state ownership, which is the ability to change the state, and if the object's reference is published, it is not the ownership of the object's exclusive state, but the ownership of the shared state with the other;2. Instance closure　　Object A is enclosed in another object B, and the path to access object A is known to facilitate thread safety, and if the data is enclosed in an object, access to the data is done through methods,

Geoquiz application There are some big loopholes, our task is to plug these loopholes, from easy to difficult, the following are the three vulnerabilities to be resolved: 1. After the user cheats, you can rotate the cheatactivity to remove the cheat marks. 2. After the cheat is returned, the user can rotate the quizactivity to eliminate the mischeater variable value. 3. The user can repeatedly click the Next button to skip to the question of peeking over the answer, thus losing the chea

--------------------------------------------------------------------From pizza import Make_pizza as MPMP (+, ' pepperoni ')MP (mushrooms ', ' green peppers ', ' extra cheese ')Assigning an alias to a module using as------------------------------------------------------------------------------------Import Pizza as PP.make_pizza (+, ' pepperoni ')P.make_pizza (' mushrooms ', ' green peppers ', ' extra cheese ')Import all functions in a module--------------------------------------------------------

categorized, that is, the training set.(2) The conditional probability estimation of each characteristic attribute under various types is obtained by statistic. That(3) If each characteristic attribute is conditionally independent (or if they are independent of each other), then the Bayesian theorem is deduced as follows:Because the denominator is the same for all categories, it is constant, so just maximize the numerator. And because a feature attribute is conditionally independent, there areT

("\ t" + topping)--------------------------------------------------------------------------------------------------------------- ---You ordered a thick-crust pizza with the following toppings:MushroomsExtra cheeseA For loop on the dictionary, looping the elements of the list in the dictionary again-------------------------------------------------------------------------------Favorite_languages = {' Jen ': [' python ', ' Ruby '],' Sarah ': [' C '],' Edward ': [' Ruby ', ' Go '],' Phil ': [' pyth

All for reference only, welcome anyone to discuss[Page] 151 [position] my_rwl.c [Type] Code error[Description] From the book to see __LINE__, is an underscore, but in fact, the built-in macro is the front and back of each of the two sliding lines, namely _ _line_ _[Page] 195 [position] studyuid.c [Type] Code error[Description] The header file for Strerror () is string.h and needs to be added before code can run[Page] 251 [position] ctrlpocess.c [Type] Code error[description] Read function declar

(Result,"%.3s%.3s%3d%.2d:%.2d:%.2d%d\n", Wday_name[timeptr-Tm_wday], mon_name[timeptr-Tm_mon], timeptr->tm_mday, timeptr->Tm_hour, Timeptr->tm_min, timeptr->Tm_sec,1900+ timeptr->tm_year); return result;}The doubt is lifted, and you can see that CTime returns a static local char array.System call Lseek Change Open file location:Handling Errors in system callsDetermine the type of error errno.Display error message Perror:The ls-a option lists hidden files:How to write LS:Stat gets file attribute

1. ExceptionsExceptions are handled using the TRY-EXCEPT code block. The try-except code block lets python perform the specified action and tells Python what to do if an exception occurs.When you use the TRY-EXCEPT code block, the program continues to run even if an exception occurs: Displays the friendly error messages you wrote, not the traceback that confuse the user.Print (5/0)Traceback (most recent): File "Exception_division", line 1, in The program is bad, let users see Traceback is not a

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Rewrite requirement 1: Dynamically generate single-linked list storage#include Rewrite requirement 2: Sort by maximum, minimum, sub-maximum, sub-minimum interval#include #includeusing namespacestd;structlinknode{intdata; structLinknode *next;};classnum{intN; intsum; Public: NUM (intx) {n=x; } structLinknode *descrease (); voidShow (linknode*phead) {Linknode*p; P=Phead; P=p->Next; cout"n="Endl; cout"sum="Endl; while(p) {coutdata; P=p->Next; } coutEndl; }};structLinknode *NUM::d esc

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1. Use the shell or Python to write a square (oldboy4.sh) to receive the number entered by the user.For example: with the + number implementation[Email protected]:~/script$ vim Oldboy_squarel.SH[email protected]:~/script$./oldboy_squarel.SHPlease Enter a number:4++++++++++++++++++++++++++++++++[email protected]:~/script$CatOldboy_squarel.SH#/biin/Bashread-P"Please Enter a number:"Num for((i=0;i)){ for((j=0;j2; j + +)) { Echo-N"+" } Echo}2. Write a isosceles triangle (oldboy2_

Notoginsengcoutshowbase; - intp=fn (); theCin>>i; + Switch(P) A { the Case -: +cout"hexadecimal converts to""decimal"Endl; - Break; $ Case 8: $cout"Octmal converts to""decimal"Endl; - Break; - Case Ten: thecout"decimal converts to""decimal"Endl; - Break;Wuyi default: the Break; - } Wu while(1); - return 0; About $}Exercise 3Exercise 5 6Exercise 9exercises One by oneExercise 14Use for to control the number of field

(1)4. Deleting elements based on valuesArray.remove (' both ')3.3 Organization List3.3.1 Use method Sort () to sort the list in a permanent orderSort () AscendingSort (reverse = True) Descending3.3.2 Use function sorted () to sort a list temporarily3.3.3 the Print List backwardsArray.reverse ()Print (array)Method reverse () permanently modifies the order of the list elements, but can revert back to the original ordering order at any time, and only need to call Reserse () on the list again3.3.4

this to an internal class or thread. The "This" itself may not be ready!(Workaround: Use engineering methods; Define threads first, add another method to start this thread)3.3 Thread closureWhen a thread does not need to share data, it is a good way to ensure thread safety by enclosing the data in threads. The program should avoid data escaping into other threads.For example, you can use local variables or threadlocal to store thread data.Ad-hoc Thread ClosureThis means that it is entirely up t

Statement: The title is from the "point of the sword". Algorithm principle please find your own book, not nonsense. Directly on the Python version code.Topic One: Give two integers a and B, ask for their and, but do not use the + and other mathematical operators.#不应该使用 recursion, too low efficiency Import = random.sample (range (1,100), 2= lst while Y! = 0 := X^y, (xy) Else: print("{} + {} = {}". Format ( LST[0],LST[1],X))Topic two: Calculate the number of 1 in binary.Import= random.randi

Similar to the multi-tasking scenario of a Web server, it is not possible to use only one thread to provide services externally. This way, efficiency and throughput are too low.However, it is not possible to create a thread with a single request because the cost of creating the thread is very high and the number of threads that the system can create is limited.So the executor appeared.The meaning of executor frame thread poolThread creation too little wasted server resources, in addition to the