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Can any one provide me a sample of Singleton in c++?
C++ Singleton design pattern
C++ different singleton implementations

I need some example of Singleton in c++ class because i have never wrote such class.
For an example in java I can declare d a static field which is private and it’s initialize in the constructor and a method getInstance which is also static and return the already initialize field instance.

Thanks in advance.

Answer 1

Example:
logger.h:

#include <string>

class Logger{
public:
   static Logger* Instance();
   bool openLogFile(std::string logFile);
   void writeToLogFile();
   bool closeLogFile();

private:
   Logger(){};  // Private so that it can  not be called
   Logger(Logger const&){};             // copy constructor is private
   Logger& operator=(Logger const&){};  // assignment operator is private
   static Logger* m_pInstance;
};

logger.c:

#include "logger.h"

// Global static pointer used to ensure a single instance of the class.
Logger* Logger::m_pInstance = NULL; 

/** This function is called to create an instance of the class.
    Calling the constructor publicly is not allowed. The constructor
    is private and is only called by this Instance function.
*/

Logger* Logger::Instance()
{
   if (!m_pInstance)   // Only allow one instance of class to be generated.
      m_pInstance = new Logger;

   return m_pInstance;
}

bool Logger::openLogFile(std::string _logFile)
{
    //Your code..
}

more info in:

http://www.yolinux.com/TUTORIALS/C++Singleton.html