SEARCH KEYWORD -- Prime number


  Understanding an interesting JavaScript map function question

With the evolvement of JavaScript, lots of new features have been added this old but robust language.  Among them are lots of functional programming language related functions like map, filter, each etc. In this post, we will cover one function map and its interesting behavior. Before dive into the details, let first take an example, do you know the output of below function call? ['1', '7', '11'].map(parseInt) You may think that it's easy and the output would be [1, 7, 11] Can you try to ru...

   JAVASCRIPT,MAP,FUNCTIONAL PROGRAMMING     2019-06-14 08:34:46

  The Strange Behavior of the void Type in TypeScript

Preface In TypeScript (TS), there is a type called void. It represents "nothing" but it's important to note that it's not the same as "nothing" in JavaScript(JS). Typically, void is used to declare the return type of functions. Although you can declare a variable as void, we generally don't do this because it serves no meaningful purpose. Let's explore why in the examples below. The void Type Declaring a Variable as void let name: void; // Declare a variable `name` with type `void`. name = 'nan...

   TYPESCRIPT,JAVASCRIPT,VOID,TYPE     2024-09-13 23:44:26

  The tic-tac-toe game with Python

In this tutorial, we will show how to build a tic-tac-toe game with Python. We will use functions,arrays,if statements,while statements, for loops and error handling etc. First, we need to create two functions, the first function will display the borad of the game: def print_board(): for i in range(0,3): for j in range(0,3): print map[2-i][j], if j != 2: print "|", print "" Here we used two for loops to loop through the map, this map is...

   Python,Tic-Tac-Toe     2013-07-30 02:49:09

  Data type in MySQL

For both small free database space and large e-commerce websites, reasonable database table structure design is essential. To achieve this, it requires us to have a full understanding of commonly used data types in database system. Below we share some knowledge about data types in MySQL.1. Numeric typesThe numeric types can be classified as : integer, float and decimal type.The so-called "decimal" refers DECIMAL and NUMERIC, they are of the same type. Strictly speaking it is not a numeric type, ...

   MySQL, Data type,VARCHAR     2013-01-01 10:56:06

  Why you should be careful about optimizations

In one of my current javascript projects, I have to deal with 3D voxel coordinates. And, sometimes, I have floating points coordinates which must be converted to integers in order to convert them into proper array index. Javascript is a wonderful language, really. However, implementations are sometimes weird, and the way to do something can sometimes have very huge impacts on the performances. Worse, sometimes the classical way is more expensive than the tricky one. So, some peo...

   JavaScript,Bitwise,Floor,Trick,Optimization     2012-05-02 11:29:20

  Demo on creating worker pool in GoLang

A worker pool is a pool where a specified number of workers(usually goroutine) created and run to pick up tasks. This can allow multiple tasks to be ran at the same time while keeping the number of workers a fixed number to avoid overuse of resource in the program. There are usually two approaches of creating worker pool. One is with fixed number of workers pre-created One is creating worker when needed until the max number of workers created In this post, we will cover the demonstration of cr...

   WORKER POOL,GOLANG,GOROUTINE     2021-01-24 05:04:00

  The Problem with Random Numbers

Today, let's talk about how to generate true random numbers. This is an extremely difficult problem, but it involves some very interesting content. First of all, the random numbers provided by programming languages are pseudo-random numbers.  The V8 engine’s official website has an article that particularly reminds everyone of this point. The built-in random numbers are not true random numbers but pseudo-random numbers. Math.random() returns a Number value with po...

   RANDOM NUMBER,TRUE RANDOM,PSEUDO RANDOM,HISTORY     2024-06-21 21:09:14

  mysql_fetch_array(),mysql_fetch_assoc() and mysql_fetch_row()

In PHP MySQL mannual. There are three functions which need to be clarified for some users who may get confused when choosing which one to use to get the result. mysql_fetch_array() : by seeting the different parameters, there are three ways to return the result set. MYSQL_ASSOC(Result set with field names as the associative indexs.It means you can use the field name as the index to get value of the specified cell). MYSQL_NUM(Result set with field names as the number indices). Or MYSQL_BOTH(...

   PHP,MySQL,resultset,comparison,mysql_fet     2011-08-05 04:53:09

  Can a === 1 && a === 2 && a === 3 be true in JavaScript?

Lots of you may be aware that there is famous interview question which asks whether a == 1 && a == 2 && a == 3 can be true in JavaScript. And the answer to this question is YES. The reason is that == will do a non-strict comparison which will evaluate a to a number and this provides the possibility of dynamically return the value when every time a is accessed. Have you ever wondered whether a === 1 && a === 2 && a === 3 can be true? At first glance, it seems this ...

   JAVASCRIPT,===,STRICT COMPARISON     2018-04-06 12:17:29

  Accurate floating point number calculation in JavaScript

In JavaScript, since floating point is defined with IEEE754,there will be some accuracy issues while doing floating point number arithmetic. Here is a function which can resolve the accuracy issue. var calc = function(num1,operator,num2,len){    var numFixs = function(num){        var arr = num.toFixed(len).toString().split('.');        return parseInt(arr.join(''));    }    switch(operator){...

   JavaScript, floating point,IEEE 754,accuracy     2012-12-27 11:07:49

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