SEARCH KEYWORD -- System programming


  Which Type of IT Career is Best For You?

Considering the growth of the information technology job market, a career in IT is an incredibly smart career move.  A career in IT can mean many things – you can become a network administration, website developer, database specialist, programmer or engineer. The job range is vast and can suit various personalities and levels of technical skill. Having a good insight into those job profiles is key to make the right decision about your career path. Here's a selection of some of the mos...

   career,IT,tips     2014-07-30 09:21:40

  Bill Gates : Ctrl+Alt+Del was a mistake

Microsoft chairman Bill Gates admitted that Ctrl+Alt+Del command was a mistake when he was in a fund raising campaign at Harvard University last week. This command was initially designed to reboot the system. David Rubenstein, the Harvard fund raising campaign chairman, asked Bill Gates : "Why when I turn on my software or computer do I need to have my three fingers to press control,alt and delete? Whose idea was that?" The answer given by Bill Gates is : "Basically because when you turn your co...

   Bill Gates,Ctrl-Alt-Del,Mistake     2013-09-26 23:28:37

  Carriage return and line feed

In programming and document editing, we may frequently encounter carriage return and line feed, i.e the well known CRLF.  But do you know about the history and difference of carriage return and line feed? Before computer came out, there was a type of teleprinter called Teletype Model 33. It can print 10 characters each second. But there is one problem with this, after finishing printing each line, it will take 0.2 second to move to next line, which is time of printing 2 characters. If a new...

   CR,CARRIAGE RETURN,LINE FEED,LF,NEW LINE,CRLF     2017-02-19 08:29:23

  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

  TIOBE: PHP is coming back

TIOBE released the programming language index for July 2013. The highlight of this month is that PHP is coming back. It ranks the fifth and has an increase of 1.54% compared to January. There are no changes in the ranking for the top 4 languages. The reason why PHP is back may be attributed to the new PHP Zend Framework that was released in September 2012, but this reason is not very convincing. PositionJul 2013PositionJul 2012Delta in PositionProgramming LanguageRatingsJul 2013Delta Jul...

   TIOBE,PHP,Zend framework,July     2013-07-09 05:22:50

  Exit main thread and keep other threads running in C

In C programming, if using return in main function, the whole process will terminate. To only let main thread gone, and keep other threads live, you can use thrd_exit in main function. Check following code: #include #include #include int print_thread(void *s) { thrd_detach(thrd_current()); for (size_t i = 0; i < 5; i++) { sleep(1); printf("i=%zu\n", i); } thrd_exit(0); } int main(void) { ...

   C LANGUAGE,MULITHREAD,MAIN THREAD     2020-08-14 21:20:04

  Differences between bashrc and profile in Linux

After login to a Linux system, the command console will show up with a prompt label such as # or ~, a shell command can be typed after this prompt and the system can execute the command thereafter. All these operations are handled by shell. Shell is a command language interpreter that executes commands read from the standard input device (keyboard) or from a file. There are different types of shells such as bash, ksh, csh etc. The most commonly used of them is bash and it's also the de...

   LINUX,PROFILE,BASH,BASHRC,.BASHRC,.PROFILE     2016-11-05 22:17:51

  Should we use Abstract class or Interface?

When we write programs, we may often get into a situation where we don't know whether we should use Abstract class or Interface when we want to define an abstract object. These two are very similar and they are interchangeable in many cases. On Stackoverflow, this question is asked lots of times and it's related to many programming languages. Also in the official documentation of PHP regarding the Abstract class and Interface, people are arguing about this. To understand this question, their dif...

   DIFFERENCE,INTERFACE,ABSTRACT CLASS,COMPARISON,OOP     2013-04-15 11:44:36

  One reason why mcrypt responds slowly

This morning one colleague came over and talked about one script which used mcrypt responded very slowly, the server configurations are fine. But the reason for the slowness is unknown. Here is one script which reproduces the issue: <?php $dmcryptText = "dummy"; $key = "foobar"; $size = mcrypt_get_iv_size(MCRYPT_BLOWFISH,MCRYPT_MODE_ECB); $iv = mcrypt_create_iv($size); //Take care $m = mcrypt_ecb(MCRYPT_BLOWFISH, $key, $dmcryptText, MCRYPT_DECRYPT, $iv); var_dump($m); When 20 requests of&...

   SOLUTION,SLOW,MCRYPT,RESPONSE,PHP     2012-09-27 12:03:16

  Check whether a remote server port is open on Linux

As a system administrator or network engineer or application developer, there is a need to check whether a port on remote server is open so that you can tell whether the service under check is running or not. In this post, we would cover a few methods to check whether a remote server port is open or not on Linux. telnet telnet is the most frequently used command on both Windows and Linux to check port. The simple usage for this command is  telnet [host] [port] When the port is open, the o...

   LINUX,TELNET,PORT,NC,NMAP     2017-12-23 11:45:20

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