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  Tips for improving PHP efficiency

0. Using single quote to replace double quote to enclose string literal, this will be a bit faster. Because PHP engine will search variables in double quoted string. 1. If a method in class can be declared as static, then make it static, this will be 4 times faster. 2. $row["id"] is 7 times faster than $row[id] 3. echo is faster than print, and you should use multiple parameters instead of string concatenation, i.e use comma(,) instead of dot(.) to concatenate string. For example echo $str1,$str...

   PHP, efficiency, tips     2012-10-01 19:39:06

  C programming tips in SPARC architecture

If you are a newbie of C programmers in SPARC architecture (For example, working on Solaris), you should pay attention to the following tips:(1) By default, SPARC is big-endian (For Endianness, you can refer http://en.wikipedia.org/wiki/Endianness). It means for an integer (short, int, long, etc), the MSB will be stored in the lower address, while the LSB will be stored in the higher address. (2) SPARC requires byte-alignment. It means for a short (2 bytes long) variable, the star...

   C     2014-06-01 03:56:30

  Configure static IP for Linux

When a Linux server is running, it has to have an IP so that other machines can talk to it. It is often desired that the server would own a static IP so that every time other machines want to connect to it, the same IP address would be used. This is extremely useful when there are virtual machines installed on a host machine where the virtual machine would start and stop now and then.  To configure static IP address for a Linux server, the /etc/network/interfaces needs to be updated. Assumi...

   LINUX,NETWORK,STATIC IP,DNS     2017-07-08 08:39:58

  Do you really understand Geolocation?

LBS(Location based service) services continue to emerge, it seems that every product has some relationship with maps. But to be honest, do you really understand what is Geolocation? Not necessarily. Although lots of products have LBS service, they can be categorized as sign, search, navigation and information display, these are functional features of the map as a software should have. However, Geolocation is not software, it is just a functional feature, a functional feature of all LBS applicat...

   geolocation,app,significance     2012-10-22 12:11:41

  Create host only network on VirtualBox

Previously we showed how to install Ubuntu in VirtualBox. What if we want to communicate with the host OS from within the Guest OS on VirtualBox? There are a few ways to do this. For example, bridged network, Host only networks. Today we will show you how to enable network communication between host OS and guest OS using host only networks. A host only network will not need to access the physical network interface of the host OS. It will create a network between different virtual machines and th...

   VIRTUALBOX,NETWORK,VIRTUAL MACHINE,HOST-ONLY     2015-12-01 09:29:13

  Disposable Email address

There is one statement which says Giving out your email address is like starting a relationship. What happens when you want to break up?Once you gave out your email address, you may take the risk of receiving big amount of junk emails. However, when we register on some websites, we must provide our Email address to receive authentication emails. If we cannot receive the authentication email, we cannot finish the registration process. Is there any alternative way?We can use disposable email, i.e,...

   Disposable email,Website,Summary     2012-05-19 12:27:14

  7 misunderstandings of DNS resolution

DNS resolution is generally considered as providing mapping between domain name and IP address, for example www.google.com maps to 74.125.71.103. There are two important reasons for doing DNS resolution: IP address is hard to remember, while domain name is human friendly Virtual host may access different contents according to the header of the host domain name(sub-domain name) Some webmasters may have some unreasonable requirements when doing DNS resolution. It mainly because they are not very...

   DNS resolution,misunderstanding     2012-10-20 12:57:16

  Why is my IP blocked at a website I visit regularly after I changed ISPs?

I just installed a new Express Card with Verizon Broadband wireless last night. Had tons of fun accessing the web from places I usually cannot, (we are in trucking) until I got to my favorite forum. It's a public place I have been to thousands of times, but instead of happily browsing all the daily news events and checking to see if the world blew up yet, I found myself blocked by a big white screen that said YOUR IP ADDRESS HAS BEEN BANNED. What can I do? I can't go to the forum owners to ...

   ISP,IP Block,StopForumSpam,Solution     2012-02-01 08:53:38

  How DNS lookup works

When accessing a website, a domain name would be needed normally. To get to the actual web server, the domain name must be mapped to an actual IP address and the IP address will be used to reach the web server. The process of finding the IP address from a domain name is called DNS lookup.  How does DNS lookup work? There are tons of domain name and IP address around the world, there must be some well-designed architecture to support fast lookup. This post will explain how this works. DNS Se...

   DNS,DNS LOOKUP     2022-09-09 23:11:03

  Smuggling data in pointers

While reading up on The ABA Problem I came across a fantastic hack.  The ABA problem, in a nutshell, results from the inability to atomically access both a pointer and a "marked" bit at the same time (read the wikipedia page).  One fun, but very hackish solution is to "smuggle" data in a pointer.  Example:#include "stdio.h"void * smuggle(void * ptr, int value){  return (void *)( (long long)ptr | (value & 3) );}int recoverData(void * ptr){  return (long long)ptr &...

   C,Pointer,Bit,Data,Atomic,Smuggle     2011-11-14 08:15:59