SEARCH KEYWORD -- essential class


  A small trick on using console.log to print data in JavaScript

When debugging JavaScript application, one may frequently use console.log to print data so that it is easy to debug when issue occurs and also helps on understand the data flow. The common way of printing a variable would be something like.  let user = { name: "test" }; console.log(user); In this case it will print: { name: 'test' } This is OK when there is no much logging or the program is not complicated. But it becomes difficult to debug if there are lots of variables to be printed ...

   JAVASCRIPT,CONSOLE.LOG,DEBUGGING     2019-09-03 10:24:24

  Permutation algorithm with JavaScript

In secondary school, we have learned permutation. Basically, for n numbers, the number of permutations for these n numbers can be calculated to n! which is called 'n factorial'. But to display all the permutations on the screen, we need to use a recursive function. The problem is how to write this function.  Next I write a program to display the permutations for n numbers with JavaScript. First, we need to understand that from these n numbers, we can first take any one number from it, and t...

   JavaScript,Permutation,Algorithm,Impleme     2011-09-21 12:02:35

  A Python assignment trap

Python has no assignment, it only has reference. Assume, we have following code snippet: >>> values = [0, 1, 2] >>> values[1] = values >>> values [0, [...], 2] Why the result is not [0, [0, 1, 2], 2], instead it goes into an infinite loop? To understand this, we need to understand some basics about Python. Python has no variables, it only has labels. When we run: values = [0, 1, 2] Python will first create a list object [0,1,2], then it labels it as values. If we later...

   Python,Assignment,Trap,Shallow copy     2013-07-19 22:08:36

  do {...} while (0) in macros

If you are a C programmer, you must be familiar with macros. They are powerful and can help you ease your work if used correctly. However, if you don't define macros carefully, they may bite you and drive you crazy. In many C programs, you may see a special macro definition which may seem not so straightforward. Here is one example: #define __set_task_state(tsk, state_value) \ do { (tsk)->state = (state_value); } while (0) There are many this kind of macros which uses do{...}while(0)...

   C,macro,C++     2014-01-23 07:16:13

  template function in class in C++

We can define template function in a class, but one thing we should pay attention to is that the member function template definition (in addition to the declaration) should be in the header file, not the cpp, though it does not have to be in the body of the class declaration itself.Example //Sorter.h#pragma onceclass Sorter{public:    Sorter(void);    ~Sorter(void);    template <class type> static void qsort(type arr[],int start,int end);};templ...

   C++,template function,class,definition,d     2011-08-07 09:39:56

  Power Grid OT Simulation System

Mini OT-Energy-System Cyber Security Digital Twin Figure-00: Power_Grid_OT_Simulation_System Environment Diagram, version v0.1.2 (2024) Project Design Purpose: The primary objective of this project is to develop a scaled-down Operational Technology (OT) digital twin/equivalent — an advanced software simulation system capable of emulating the functionality of an small-sized 18KW (560+MkWh/year) hybrid power grid. This system will meet the requirements for cybersecurity training, exercises...

       2024-10-13 09:00:12

  Art of code comment

Note : This post is just for fun. Please be careful about these tricks. Code comment is to provide complementary comment to abstract codes. We will introduce two comment styles while we are debugging our codes. we should avoid these styles in production codes. 1. if else style Only execute eatKfc() //* eatKfc(); /*/ eatMcdonalds(); //*/ Only execute eatMcdonalds() /* eatKfc(); /*/ eatMcdonalds(); //*/ Execute both //* eatKfc(); //*/ eatMcdonalds(...

   Comment,Style     2013-08-19 04:19:40

  Will PHP __autoload() function really affect performance?

IntroductionRegarding to PHP performance, the most frequently discussed is the __autoload() function. Many people say that this function will affect the performance very much, some other people say that opcode will affect __autoload() as well. So we will have some tests on these two.EnvironmentPHP 5.3.9 -- Launch under fastcgi modeNginx 1.1.12eAccelerator 0.9.6.1ScreenshotsLaunch pageeAccelerator(In php.ini) configurationFile structure(each Test file has over 6000 lines of code)Testing With e...

   PHP,__autoload(),opcode,performance     2012-05-09 11:25:26

  Gcd Algorithm with JavaScript

How to find the greatest common divisor between two integers? We may encounter this problem frequently in interviews or other occasions. An efficient metho to find gcd is the Euclidean algorithm, which uses the division algorithm in combination with the observation that the gcd of two numbers also divides their difference: divide 48 by 18 to get a quotient of 2 and a remainder of 12. Then divide 18 by 12 to get a quotient of 1 and a remainder of 6. Then divide 12 by 6 to get...

   JavaScript,Algorithm,Gcd,Implementation,     2011-09-21 15:57:32

  9 Ways to Create Thread Pools with Java Executors

In Java, the Executors class provides a variety of static factory methods to create different types of thread pools. When learning about thread pools, the Executors class is indispensable. Mastering its usage, principles, and scenarios will enable you to apply it smoothly in actual project development. Here are some commonly used methods, which I will explain one by one: newCachedThreadPool(): Creates a cached thread pool. If a thread has not been used for 60 seconds, it will be terminated and ...

   TUTORIAL,JAVA THREAD     2024-07-19 23:07:09

RECENT