Question

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

我需要一些C ++类中的Singleton示例，因为我从未编写过这样的类。对于java中的一个例子，我可以声明一个私有的静态字段，它在构造函数中初始化，并且方法getInstance也是静态的，并返回已经初始化的字段实例。

提前致谢。

Answer 1

//.h
class MyClass
{
public:
    static MyClass &getInstance();

private:
    MyClass();
};

//.cpp
MyClass & getInstance()
{ 
    static MyClass instance;
    return instance;
}

Answer 2

例：
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..
}

更多信息：

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

C ++ Singleton类getInstance（作为java）

2 个答案: