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  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

  Supercolliding a PHP array

Did you know that inserting 2^16 = 65536 specially crafted values into a normal PHP array can take 30 seconds? Normally this would take only 0.01 seconds. This is the code to reproduce it: <?php echo '<pre>'; $size = pow(2, 16); // 16 is just an example, could also be 15 or 17 $startTime = microtime(true); $array = array(); for ($key = 0, $maxKey = ($size - 1) * $size; $key <= $maxKey; $key += $size) { $array[$key] = 0; } $endTime = microtime(true); echo 'Inserting...

   PHP,Array,hashtable,Slow,Colliding     2011-12-29 09:02:01

  Understanding Slice Behavior in Go

In Go, understanding how slices behave when passed to functions is crucial for writing efficient and bug-free code. This behavior is often a source of confusion for many developers, especially those new to the language. In this article, we'll explore the difference between passing slices by value and by reference, and how it impacts the modification of slices within functions. Introduction In Go, slices are a fundamental data structure used to work with sequences of elements. They are essentiall...

   PASS BY REFERENCE,ARRAY,SLICE,PASS BY VALUE     2024-03-10 06:43:51

  How many bytes a boolean value takes in Java?

Have you ever wondered how many bytes a boolean value takes in Java? One byte, this might be the answer comes out of your mind right away. But is it? Let's dig in more. Per Oracle documentation on boolean value definition, there is below statement: boolean: The boolean data type has only two possible values: true and false. Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its "size" isn't something that's precisely defin...

   JAVA,INTERVIEW,SIZE,BOOLEAN     2020-02-29 02:49:18

  + operation on JavaScript objects

In JavaScript, there are two types of values: primitive and object. Primitives consist undefined, null, boolean, number and string. Other values such as array and function are objects. When applying + operation on different type of values, there would be three kinds of type conversion. Primitive conversion Number conversion String conversion There three type conversions have corresponding abstract operations in JavaScript: ToPrimitive(), ToNumber(), ToString(). For number additi...

   JAVASCRIPT,PROGRAMMING     2018-10-12 22:19:12

  ByteBuffer in Java

ByteBuffer is introduced in java.nio since Java 1.4. It provides a way of representing raw structured data such as from a file or from network. It enables fast access of underlying data compared to traditional ways like byte[] Prior to Java 1.4, if you want to represent a structured raw data, you need to create a byte[] and then having a set of checks to delimit the byte array to get the expected tokens. There are three ways to create a ByteBuffer: Wrapping an exiting array by calling ByteBuffe...

   JAVA,BYTEBUFFER,ALLOCATION     2015-07-08 03:17:44

  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

  JSON in JavaScript

When sending an AJAX request to the server, the response can have two formats : XMLHttpRequest.responseXML to access data with XML format and XMLHttpRequest.responseText to access data with string format. XML is the standard data transfer format, but one weakness is it's troublesome to parse and retrieve the data. JSON(JavaScript Object Notation) is a light weight data interchange format, we call it the JavaScript object representation. The advantage of using JSON as the data format is itself is...

   JSON,JavaScript     2013-05-04 23:25:57

  The hidden risk of passing slice as function parameter

In Go's source code or other open source libraries, there are lots of cases where a slice pointer is passed to function instead of slice itself. This brings up a doubt why not passing slice directly as its internal is backed by an array pointer to point to underlying data? For example, in log package, the formatHeader function takes a parameter buf as type *[]byte instead of []byte. func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {} Let's understand the r...

   GOLANG,SLICE,SLICE POINTER     2020-12-13 06:11:14

  Illiterate Programming

Donald Knuth cleverly imprisoned the phrase "Literate Programming" - if you're not documenting your source with his particular methodology then you must be a proponent of "Illiterate Programming," which sounds truly awful. I very much believe in documented code but I think no amount of pontification in English will ever make a piece of code clearer than the code itself (I'm not talking about project or API documentation). I'm also not talking about the super...

   Programming,Illiterate     2012-02-10 06:20:52

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