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  System programming is still there

System programming is the practice of writing system software. System software lives at a low level, interfacing directly with the kernel and core system libraries. Your shell and your text editor, your compiler and your debugger, your core utilities and system daemons are all system software. But so are the network server, the web server, and the database. These components are entirely system software, primarily if not exclusively interfacing with the kernel and the C library. But nowadays more...

   System programming     2014-02-27 05:46:48

  What surprise Google brings us in Nexus 5?

Because Nexus 4 performed well after release, many people are confident of the performance of the upcoming Nexus 5. It is manufactured by LG and equipped with attractive configurations. LG Nexus 5 will have Android 5 installed, as for hardware, it will have a 5.2 inch screen with a resolution of 1920x1080  Also the processor will be a 2.3GHz Quad-Core processor. The exciting part is it has a 4GB(Some says it's 3GB) memory which is larger than almost all current Android devices which have 2G...

   Nexus 5,Google,LG     2013-04-08 07:37:41

  A turing machine in 133 bytes of javascript

Multiply turing machine The fact it took me 20 lines of javascript to implement a nondeterministic turing machine simulatorlast week kept me up at night. All weekend. Too much code for something so simple and I kept having this gut feeling implementing a basic version shouldn’t take more than 140 bytes. Sunday afternoon I sat down for about an ...

   Turing machine,JavaScript,Simple code     2011-11-28 09:27:28

  What does session_destroy() do in PHP?

In PHP manual, the description for session_destroy() function is : session_destroy() destroys all of the data associated with the current session. It does not unset any of the global variables associated with the session, or unset the session cookie. To use the session variables again, session_start() has to be called. I am confused about this description. If this function destroys all session data, then why the global variables associated with the session are not unset? Why can we u...

   session_destroy,session_start     2013-08-31 09:59:05

  Why exception would be thrown when deleting element while looping through HashMap in Java

HashMap and other Collection types are frequently used in Java application programming. This post will explain why exception would be thrown when deleting element with Map.remove() while looping through a Map using Iterator. This issue would also occur to other Collection types such as Set, List. Below is a sample code snippet demonstrating the exception thrown. Map<String,String> map = Collections.synchronizedMap(new TreeMap<String,String>()); map.put("key1","value1"); map.put("ke...

   JAVA,HASHMAP,CONCURRENTMODIFICATIONEXCEPTION     2018-06-30 12:49:09

  Using vi key bindings in bash and zsh

Takeaway: If you prefer to use vi or vim for command-line editing, you can configure shells to use vi key bindings instead of emacs-style key bindings. Here’s how. By default, most shells use emacs-style key bindings for command-line editing and modification. For users of vi or vim, however, you can instead configure shells to use vi key bindings instead. This is done by editing ~/.bashrc in the case of bash, or ~/.zshrc in zsh a...

   vi,Linux,Zsh,bash,key binding     2012-02-07 06:22:36

  Google releases new app to improve the accuracy of indoor positioning

Google Maps, Bing Maps, and some map providers have offered indoor map service such as in  the airport, major shopping malls and stadiums for some time. The problem is that these indoor maps can not precisely tell you which floor you are on a map, the GPS obviously can not work very well in this environment, WiFi and GPRS positioning is not very precise. Google announced the improvement program of Google Maps for accurate indoor positioning. The current owners of these places will cooperat...

   Google Map,Indoor service,Positioning     2012-04-08 09:46:53

  The craziest Javascript implementations

Since its birth in 1994, Javascript has come a long way. Today it’s one of the most popular programming languages on the web because of high popularity of AJAX based web-applications. Also the rise of micro-frameworks such as jQuery (also Prototype, Moo Tools etc) which have reduced dramatically the complexity of code developers needed to write, it is well tested, has a ton of plug-ins, has a large development community and reduced development time.And lately even Server-S...

   JavaScript,Crazy implementation,JVM,Turing machine     2012-01-03 12:09:42

  How to undo git changes?

When using git for version control, there is frequent need on undoing commits due to some unexpected changes. This post will introduce how to undo changes with git command in different cases. Undo commit A common undo case is that some commit needs to be reverted as the commit contains error. In this case, the code is already committed. The command to revert the commit is git revert HEAD This command will add new a commit to the existing head to undo the previous commit. It will not change the p...

   GIT,GIT RESET,GIT REVERT,GIT CHECKOUT     2019-12-28 02:21:47

  Recursive class initialization in Java

When a Java class is referenced and initialized, it has to go through the loading and linking first. Once the loading and linking complete successfully. The class will be initialized. The static variables and constant variables will be initialized during this process. Once the class is initialized, it is ready for use. If when class A is initialized and it is referencing a class B, the class B will also get initialized. But what will happen if class B is referencing class A as well? This is call...

   Java,JVM,class initialization,static final     2015-04-15 21:04:29

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