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;}}}} Simple implementations are unsafe for threads, because in the case of multithreading, it is possible to produce multiple singleton instances. In the case of multithreading, multiple singleton instances are generated if multiple threads are judged (instance = null) without creating an instance. For a simple implementation, singleton instantiation is not created by application startup, so we call it "lazy instantiation", which avoids instantiating unnecessary instances when the ap

6. IPtales firewall rulesAssume that our server server1 runs Apache and sshd (sshd can be modified in the configuration file without running on the standard port ). The ethO Nic is connected to the Internet, and the ethi is connected to the LAN. The Administrator logs on to server2 at home by dialing (the private network TP is 192.168.0.12) and then logs on to server1. The command is as follows:To prevent IP spoofing, you can also bind the NIC address of Server

1. Invisible backup battery Your cell phone is underpowered. to enable it to continue using it, press the * 3370 # key and the phone will restart. After it is started, you will find that the power usage has increased by 50%. When the hidden backup battery is used up, you have to charge it. When you recharge the battery, the invisible backup battery is also charged. You can use this method when the power usage is low next time. I know this is usefu

to basic Linux shell script Learning (2) This section introduces the basic course of Linux shell script. It introduces shell commands and process control in detail. This section introduces three types of commands, which should be compared during learning. The basic course of Linux shell script describes the beginning, comments, variables, and environment variables of the basic syntax. Here we will introduce the first part of the shell command and con

attributes: Shell> ls-l/usr/local/mysql Total 40 Drwxrwxr-x 2 root 4096 Feb 27 20:07 bin Drwxrwxr-x 3 root 4096 Feb 27 20:07 include Drwxrwxr-x 2 root 4096 Feb 27 :07 info Drwxrwxr-x 3 root 4096 Feb 27 20:07 lib Drwxrwxr-x 2 root 4096 Feb 27 20:07 libexec Drwxrwxr-x 3 root 4096 Feb 27 :07 man Drwxrwxr-x 6 root 4096 Fe

that it should be extrapolate.(1) Create a new directory in the root directory learn/, and then create a directory smarty/in the learn/. The libs/copy of the directory just extracted to smarty/, and then in smarty/new Templates directory, templates new cache/,templates/,templates_c/, config/.(2) Create a new template file: Index.tpl, put this file in the Learn/smarty/templates/templates directory, the code

("liao",-15933 ), Array ( quot; lie quot;,-15920 ), Array ("lin",-15915 ), Array ( quot; ling quot;,-15903 ), Array ("liu",-15889 ), Array ( quot; long quot;,-15878 ), Array ("lou",-1, 15707 ), Array ("lu",-15701 ), Array ("lv",-15681 ), Array ("luan",-15667 ), Array ("lue",-15661 ), Array ("lun",-1, 15659 ), Array ("luo",-15652 ), Array ("ma",-15640 ), Array ("mai",-15631 ), Array ( quot

[C ++ exploration tour] Part 2 Lesson 1: object-oriented exploration, the shocking inside story of string Introduction 1. Part 2TheLesson 1:Object-oriented research, the shocking inside story of string 2. Preview of the second lesson: set off the "class" header (

In fact, the deepest reason for all deadlocks is: resource competitionSQL server deadlock 1:A user A accesses table A (locking table A) and then accesses Table BAnother user B accesses Table B (Table B is locked) and then attempts to access TableAt this time, user A has locked Table B because user B has to wait for User B to release Table B to continue. Well, the old man will have to wait honestly.Similarly

1.1 null1.2 kernel interface = system call. Kernel + software (System Utility, application software, Shell, public function library) = operating system.1.3 password file/etc/passwdSAR: X: 205: 105: Stephen Rago:/home/SAR:/bin/KShLogin Name, encrypted password, user ID (205), group ID (105), comment, start directory (/home/SAR), shell program (/bin/KSh ). Shell: Command Line interpreter. In Linux, the default value is Bourne-again. Mac OS default tenex C.1.4 file system. Root directory /. Stat an

($ data )); ?> Reference: ereg_replace () Return value: string Function type: data processing Content Description: This function converts the ancient Slavic string to another string. THE from and to parameters are characters and their meanings are as follows: K-koi8-r Ws-windows-1251 Iso8859-5 A x-cp866 D x-cp866 M-x-mac-cyrillic Syntax: string crypt (string str, string [salt]); Return value: string Function type: encoding Description: This function encrypts the string with the standard DES

The representation of the unsigned intToday, I encountered a bug when I wrote the heap sort. void builMaxHeap( int *arr,unsigned int heapSize){ unsigned int i; for(i=heapSize/2-1; i>=0;--i){ std::coutistd::endl; //maxHeap(arr,i,heapSize); 这里暂且注释掉 } } This is really the whole dead man, thought it was the wrong program, the output of the

1) how to create an object: 1. Use constructor, for example:Var obj = new Object () // var can be omittedVar obj = new Date ()2. Use object literals ),For example:Program codeVar obj = "123" // create a String objectVar obj =/^ abc $ // create a RegExp objectIn a more complex scenario, we can directly generate a custom property-only object:Program codeVar obj = {

. NET Framework (part 2) (1) [Author: Unknown addition time: 8:11:13] ! [6.0 programmers, your first choice may be a tested and effective old method. However, if possible, you 'd better get rid of old habits and adopt the new. NET system class. Why? Because the use of the system class makes it easier for your code to be transplanted to other. NET languages and future VB. NET versions.Dim str