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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

  A collection of color schemes for some famous websites in China

Each website has a color scheme which identifies itself. By looking at one color, we can know which website it is for. These color schemes can be identified from their logos, nav-bars, background etc. We collect some color schemes for some famous Chinese websites. Alibaba (#f90)   Baidu (#0000cc)   Huawei (#e30a12)   HTC (#69b40f)   JD (#c91623)   Renren (#105ba3)   Sina (#e4351e)   Sohu (#fdd000)   Taobao (#ff4400)   Tencent (#0397de)   Tmall (#...

   Website,Color scheme,China     2013-08-21 12:32:14

  Will PHP __autoload() function really affect performance?

IntroductionRegarding to PHP performance, the most frequently discussed is the __autoload() function. Many people say that this function will affect the performance very much, some other people say that opcode will affect __autoload() as well. So we will have some tests on these two.EnvironmentPHP 5.3.9 -- Launch under fastcgi modeNginx 1.1.12eAccelerator 0.9.6.1ScreenshotsLaunch pageeAccelerator(In php.ini) configurationFile structure(each Test file has over 6000 lines of code)Testing With e...

   PHP,__autoload(),opcode,performance     2012-05-09 11:25:26

  Error handling style in C

Following are three error handling styles in C.Which one you like the most? Or you don't like any one?1. /* Problem : Not enough. Easy to be wrong */int foo(int bar){        int return_value = 0;        int doing_okay = 1;        doing_okay = do_something( bar );        if (doing_okay)        { ...

   C,Error handling style,Goto,Nested if     2012-04-24 06:51:00

  Let browser prompt for storing password when doing AJAX login

In Web 2.0 era, more and more web applications are using AJAX to replace the traditional HTML form element to perform user login. This usually provides a better user experience than form submission. But it also brings a side effect to the end users. That is the browser will not prompt the user whether s/he wants to save the password so that s/he no needs to enter the username/password again when visiting the same site next time. Below is the code snippet which does the AJAX login.  <scri...

   AJAX,Browser,Login,Password     2015-06-04 10:02:46

  HeartBleed: Inside the heart, what happens to a normal WEB user?

To be brief, our email, IM, facebook etc. are at the risk, so try to minimize the access in these few days. Especially we should try to avoid log into our internet-banking, because we may expose our user id and password. Also later when the service providers fix the bug, we would better to change a new password for all the web accounts that are important to us. Here comes the technical explanation. You might notice before that a lot of websites use URL starting with "https". For example, https:/...

   HeartBleed,Analysis     2014-04-09 22:41:43

  Tips and tricks about JavaScript from Google

JavaScript is now a very popular client side language. It's flexible, powerful but easy to make mistakes. So good programming style is better for you to write efficient and readable JavaScript codes. Here are some tips and tricks about JavaScript from Google. True and False Boolean Expressions The following are all false in boolean expressions: null undefined '' the empty string 0 the number But be careful, because these are all true: '0' the string [] the empty array {}&n...

   JavaScript, Google, Coding standard     2013-02-26 23:11:03

  C++/CLR int to System::String^

In C++/CLR (for Microsoft), sometimes we need to convert int to System::String type or vice versa. The simple way is :From System::String^ to int int num= int::Parse(str); // System::String^ to int From int to System::String^ System::String^ str = num.ToString(); // int to System::String^For all the other data types, similar ways can be adopted....

   C++,CLR,Microsoft,System::String,Convert,int     2011-12-15 12:47:22

  An experience of fixing a memory-corruption bug

During the last 4 months, I was disturbed by a memory-corruption bug, and this bug will cause program crash. Until last Monday, I found the root cause and fixed it. This debug process is a difficult but memorable experience, so I will share it in this article.   My program works as a SMS Hub. When it receives a SMS, it will allocate a structure in heap memory like this: typedef struct { ...... int *a[8]; ...... } info; After processing the SMS, the program will free the m...

   c, debug, unix, solaris, multi-thread     2014-05-04 03:52:43

  Apache Tomcat Installation and Configuration

When you want to install Apache Tomcat on Windows System. You may find that there are some tricky parts. Next I will elaborate the steps to install and configure Tomcat. If you want to install Tomcat as a service without GUI. You need to download the 32-bit Windows.zip from http://tomcat.apache.org/download-70.cgi. After downloading this zip file. You need to unzip this file to the directory which you want to put this software to. After unzipping, you can go to the bin directory and find t...

   TOMCAT 7,WINDOWS,APACHE,INSTALL,CONFIGUR     2011-04-10 14:17:21

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