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  Why 0.1+0.2 != 0.3

In programming languages such as JavaScript, c/c++, Java and Matlab, you will find that you will get unexpected result when doing float point calculation. For example, when calculating 0.1 + 0.1, you will not get 0.3: > 0.1 + 0.2 == 0.3 false > 0.1 + 0.2 0.30000000000000004 Don't be surprised of this result, this is the end result of IEEE 754 standard, float point number cannot be accurately represented according to IEEE 754 because: No enough memory is allocated for representing the num...

   float point,comparison,JavaScript     2014-11-19 05:32:46

  Understand diff in Unix

diff is an important tool program in Unix. It is used to compare differences of two files, it is the foundation for code version control. If you type : $ diff <file_before_change> <file_after_change> diff will tell you what's the difference between these two files. The result may not be so easy to understand, so now I will show you how to understand diff. 1. 3 formats of diff diff has 3 formats due to historic reasons. normal diff context diff unified diff 2. Demo files For easy d...

   diff,Unix,version control,git     2012-09-03 10:49:36

  Understand Virtual DOM

With the popularity of React, the internals and implementation of Virtual DOM has becoming top discussed topic in tech communities and interviews. This post will give an introduction of Virtual DOM and how to implement a simple Virtual DOM logic. How to understand Virtual DOM In early days, front end developers would update a webpage view based on the data status change(usually after making AJAX call). But it brings performance penalties when there is frequent update as it would cause page reflo...

   JAVASCRIPT,DOM,VIRTUAL DOM     2019-12-07 23:43:04

  <=> operator in MySQL

Have you ever seen "<=>" in a SQL query while using MySQL? Does it mean less and equals to and greater than? Actually if you consider it as the union of <= and =>, great, you are close to it. This is one form of equal operator in MySQL, it has the similar meaning to the = operator with some subtle difference. According to MySQL documentation, <=> is NULL-safe equal. This operator performs an equality comparison like the = operator, but returns 1 rather than NULL if both operand...

   MySQL,NULL safe,<=>     2014-03-24 06:23:22

  Life in Apple design team

While in mentioning about Apple, everyone of us will think of the amazing products shipped out by Apple such as iPhone and iPad. We are all impressed by its smooth design and handy user experience. But as a outsider do you know the story behind the amazing design of Apple? Apple has a team of world class designers and they are leading the fashion of design. What's the life in Apple's design team? Ben Williamson from Apple shared one story of him which can give us some hints on what the life is ...

   Apple,Design,Perfect     2014-01-02 07:00:27

  One good way to use optional parameter in function

In GoLang, it doesn't support method overloading like in Java, hence sometimes it would be a headache to create functions to construct new structs with different parameters.  Normally, we would construct the new function as below when want to let others create a new struct instance with explicit function call. type Queue struct { Name string } func NewQueue(name string) *Queue { return &Queue{name} } But with the scope and complexity of the struct increases, there might be more prope...

   OPTION PATTERN,VARIADIC FUNCTION,OPTIONAL PARAMETER     2020-09-18 21:45:29

  How does iPhone 5 compete with the latest Android and Windows Phone?

Apple's latest release of the iPhone 5 finally resolves some key issues: the larger screen, high-speed 4G LTE network, as well as a higher pixel front camera, which previously were the advantages of the Android phone. In addition, one-piece aluminum housing also gains praise. How does IPhone 5 compete with the latest Android and Windows Phone? In fact, Apple is now facing more intense competition.The most significant upgrade is the new display, 4-inch retina display compared with the old is a gr...

   iPhone 5,Android,Windows Phone,Comparison     2012-09-12 21:58:27

  Deploy the political campaign with all guns blazing through predictive dialer

The US Presidential election 2016 is turning out as more of a global event day by day, as it’s going to influence numerous countries around the world in one or other way. It is getting more and more intense as D-day is coming closer. You can experience the energy in candidates’ vociferous debates, where they put forward their agendas, their point of views, which give us the glimpse of their philosophy and their vision towards the betterment of the country. Whether it is Democratic o...

   AUTO DIALER,PREDICTIVE DIALER,CLOUD AUTO DIALER,POLITICAL     2015-09-28 12:33:14

  Check out Google Reader substitutes

It's only a few hours left that Google Reader will be shut down Since Google decides to decommission such a good product, many people are disappointed about Google. The gene of Google is completely different from Facebook, The strategy of promoting Google+ everywhere is becoming a bit offensive. As a heavy user of Google Reader, people have to start looking for an alternative, Below we give a comparison of different Google Reader substitutes. And we compare them with following parameters: Lload...

   RSS reader,Google Reader,Feedly     2013-06-30 08:46:42

  Ways to check existence of JavaScript object

The design of JavaScript is not so sophisticated. It's very easy for us to make mistakes if we are not very careful when using JavaScript. For example, to check the existence of JavaScript object. Now we want to check whether a global object myObj exists or not, if it doesn't exist, we declare it. The pseudo code for this is : if(myObj not exist){ declare myObj; } You may think it's very easy to write the code. In fact, it is much more difficult than we may think. Juriy Zaytsev says there are m...

   JAVASCRIPT,OBJECT,EXISTENCE     2020-09-12 02:14:02

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