SEARCH KEYWORD -- Weak reference
Undefined property or variable in JavaScript
JavaScript is a weak type language, and also you can use a variable or property where it's undefined. If we don't have correct ways to check whether a property or variable is defined, we may get unexpected results when we try to access the,. How can we check whether a property or variable is undefined? This is actually a somewhat tricky question. Let's start off with some facts about undefined and then see what kind of function is consistent with the ones we care about. JavaScript attaches type...
Property,Undefined,Array,JavaScript 2014-07-24 06:56:07
Coding skill and the decline of stagnation
I am a decent programmer. I know a decent amount of computer science theory, I can type correct code fairly easy. I don’t let my classes expand too much. But I still struggle some with math, and I have a tendency to have too many cross-dependencies in my code. I used to think I was an awesome programmer. One of the best. After I made a game in the first programming lesson in school, I got told to don’t bother showing up for the rest. I was the one who taught all my friends wh...
Coding style,SOPA,Stagnation,Decline 2012-01-14 12:05:10
A trap in PDOStatement::bindParam
First, let's check out below codes: <?php $dbh = new PDO('mysql:host=localhost;dbname=test', "test"); $query = <<prepare($query); $bind_params = array(':username' => "laruence", ':password' => "weibo"); foreach( $bind_params as $key => $value ){ $statement->bindParam($key, $value); } $statement->execute(); What is the SQL executed finally? Is there any problem with above codes? Many people may think the query executed is : INSERT INTO `user` (`username`, `password...
String intern in Java
In Java, == is used to compare whether two objects have the same memory location, equals() is usually used to compare whether two objects have the same time and the same state. When comparing two strings, normally we just want to know whether they have same content, so we can choose equals(). But since String comparison is so frequently needed, Java has worked on the String class to make == workable when comparing two String literals. The String class maintains a pool of emp...
How do Silicon Valley companies recruit
There are a lot of friends asking me about the basic flow of how Silicon Valley companies recruit engineers. As a candidate, I tried Facebook, Google, Yahoo, Oracle, and I received offer from all these companies. As an interviewer, I have interviewed no less than 300 people and I know about the process of recruitment. I write this article with the hope of inspiring people who want to go to Silicon Valley or who are preparing for interviews or who are in the design of the recruiting process...
Facebook,Interview,Experience,Silicon Valley 2012-05-15 06:36:52
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...
App's user value doesn't necessarily bring business value
There is an old saying in Internet world, you can get business value as long as you can achieve user value. Is this statement outdated in mobile Internet era? This statement originated from PC Internet era, but now the time users spend on PC drops and user behavior tends to be stable and conservative. In contrast, people are more willing to stay on mobile devices. The difference between PC and mobile is that users are freely to move around on PC end. People can navigate from one link to another ...
App,Business value,User value 2013-06-25 10:52:12
A Perl Regular Expression That Matches Prime Numbers
perl -lne '(1x$_) =~ /^1?$|^(11+?)\1+$/ || print "$_ is prime"' Can you figure out how it works? I give an explanation below, but try to figure it out yourself. Here is what happens when you run it: $ perl -lne '(1x$_) =~ /^1?$|^(11+?)\1+$/ || print "$_ is prime"' 1 2 2 is prime 3 3 is prime 4 5 5 is prime 6 7 7 is prime 8 9 10 11 11 is prime Here is how it works. First, the number is converted in its unary representation by (1x$_). For example, the number 5 gets converted into 1x5, which is ...
Perl,Regex,Regular expression,Prime number,One line 2011-12-26 08:42:00
What will the value of Integer.valueOf(127) == Integer.valueOf(127) be in Java?
Do you really understand how Java does the integer comparison? OK, ignore the statements in the post title. What we are interested in is another set of comparison statements. Let's first see below code snippet. public class IntegerComparison { public static void main(String[] args) { Integer a = 127, b = 127; Integer c = 128, d = 128; System.out.println(a == b); System.out.println(c == d); } } What do you think the output will be? Are they both displaying true? You will find out t...
Why Objective-C is Hard
As an active member of "The Internet" and vocal Objective-C coder, I get a lot of questions surrounding the language. They're often framed around thinking about learning the language or trying to write an app, but they also usually involve a phrase like "Objective-C looks really hard" or "what are all those minus signs about?" Both of these are pretty good questions, and I'd like to address why someone might be more hesitant to jump into iOS or OS X development compared to, say, Ruby or J...
Objective-C,difficult,hard,reason,analysis 2012-03-07 05:11:28
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