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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

  How to write your own DSL in Ruby

DSL(Domain Specific Language) is a language defined to fulfill some domain specific requirements to ease people's work. It can be used to define attributes and actions of a domain easily and cleanly. And it is often created based on some common observations or micro patterns of some domain. In Ruby world, there are quite a few places people can find DSL. For example, Ruby itself, Chef recipes. To create a class in Ruby, the traditional OOP way would look like. class User @name = nil @email =...

   RUBY,DSL,TUTORIAL     2017-03-04 09:40:34

  How to reset root password in MySQL 8

The user password in MySQL is stored in the user table, the password reset is actually to change the value of record in this table. To change the password in case the password is forgotten, the idea is to bypass the authentication of MySQL and get into the system and update the record password value with SQL command. In MySQL 5, one can start MySQL service with --skip-grant-tables option, this option will tell the service to skip loading the grant tables when starting, hence the root user can lo...

   MYSQL,PASSWORD,MYSQL 8     2018-12-24 21:27:13

  Hash Tables in Javascript

IntroductionHash tables are a permutation of associative arrays (i.e. name => value pairs). If you use PHP, then you are very familiar with this type of data structure already since all PHP arrays are associative.The Javascript language implements very loose and somewhat limited support for associative arrays. Any JavaScript array can use other objects as keys, making it a hash, but there exists no formal constructor for initializing them and it is more or less unweildy to work with. A short ...

   JavaScript,Hashtable,Implementation,Array     2011-11-26 02:43:40

  Execute PHP from a .html File

How can I execute PHP code on my existing myfile.html page?:When a web page is accessed, the server checks the extension to know how to handle the page. Generally speaking if it sees a .htm or .html file, it sends it right to the browser because it doesn't have anything to process on the server. If it sees a .php extension (or .shtml, or .asp, etc), it knows that it needs to execute the appropriate code before passing it along to the browser. Here is the problem: You find the perfect ...

   PHP,HTML,PHP in HTML,AddType     2011-12-26 14:01:20

  A Javascript When Function

function when(conditionFunc, execFunc, interval){ if (conditionFunc()){ execFunc(); }else{ setTimeout(function(){ when(conditionFunc, execFunc, interval);}, interval); } } You have some code which should only execute when a condition is true. E.g. You have code which relies on a javascript library but can't be sure the library has loaded yet and don't want the code to execute until it has. This is common if you have a bookmarklet which injects more than one <...

   JavaScript,When,Implementation,When function     2012-02-24 05:08:34

  JavaScript: Passing by Value or by Reference

In JavaScript, we have functions and we have arguments that we pass into those functions. But how JavaScript handles what you’re passing in is not always clear. When you start getting into object-oriented development, you may find yourself perplexed over why you have access to values sometimes but not other times. When passing in a primitive type variable like a string or a number, the value is passed in by value. This means that any changes to that variable while in the function are com...

   JavaScript,Function,Pass by reference,Pa     2011-07-28 11:05:25

  CSS Box Shadow Illustration

Used in casting shadows off block-level elements (like divs)..shadow { -moz-box-shadow: 5px 5px 5px #ccc; -webkit-box-shadow: 5px 5px 5px #ccc; box-shadow: 5px 5px 5px #ccc; }The horizontal offset of the shadow, positive means the shadow will be on the right of the box, a negative offset will put the shadow on the left of the box.The vertical offset of the shadow, a negative one means the box-shadow will be above the box, a positive one means the shadow will be below the box.The blur r...

   CSS,Box Shadow,Apple,Chrome,Safari,IE,Il     2011-06-30 04:03:38

  PHP buffer: output_buffering and ob_start

buffer is one piece of memory section, it is usually 4Kb in Linux. It is mainly used between different devices with different speed or different priorities. With buffer, the waiting time between different processes will be reduced. Here is one simple example, when you type something in a text editor, every time when you type a character, the operating system will not write it to the disk directly, instead it will write it to buffer first When the buffer is full, the data in the buffer will be wr...

   PHP buffer,output_buffering,ob_start     2013-06-20 22:54:15

  CSS position explained

CSS has two very important properties on determining the position of an element in webpage: display and position. display is used to determine how elements are grouped and displayed on the page. While position is used to determine the exact position of an element on a page. And this post would explain position property in detail. position is used to determine the exact position of an element on a page. It has five possible values. static relative absolute fixed sticky sticky is supported start...

   CSS,STICKY,CSS3     2019-11-22 19:57:52

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