C + + Single case mode application instance _c language

This article describes the C + + Single example mode and its related application methods, share for everyone to reference. The specific methods are analyzed as follows:

Defined:

A class has and has only one instance, and provides a global access point to access it.
Points:
1, the class can only have one instance;
2. This instance must be created by itself;
3. This instance must be provided to the whole system.

Implement one: Single case pattern structure code

The Singleton.h file code is as follows:

#ifndef _singleton_h_
#define _SINGLETON_H_

class SINGLETON
{public
:
  static singleton* GetInstance ();
Protected:
  Singleton ();
Private:
  static Singleton *_instance;

#endif

The Singleton.cpp file code is as follows:

#include "singleton.h"
#include <iostream>
using namespace std;

singleton* singleton::_instance = 0;

Singleton::singleton ()
{
  cout<< "create Singleton ..." <<endl;
}

singleton* singleton::getinstance ()
{
  if (0 = _instance)
  {
    _instance = new Singleton ();
  }
  else
  {
    cout<< "already exist" <<endl;
  }

  return _instance;
}

The main.cpp file code is as follows:

#include "singleton.h"

int main ()
{
  Singleton *t = Singleton::getinstance ();
  T->getinstance ();

  return 0;
}

Implementing Two: Printer instances

The Singleton.h file code is as follows:

#ifndef _singleton_h_
#define _SINGLETON_H_

class SINGLETON
{public
:
  static singleton* GetInstance ();
  void printsomething (const char* str2print);
Protected:
  Singleton ();
Private:
  static Singleton *_instance;
  int count;
};

#endif

The Singleton.cpp file code is as follows:

#include "singleton.h"
#include <iostream>

using namespace std;

singleton* singleton::_instance = 0;

Singleton::singleton ()
{
  cout<< "create Singleton ..." <<endl;
  count=0;
}

singleton* singleton::getinstance ()
{
  if (0 = _instance)
  {
    _instance = new Singleton ();
  }
  else
  {
    cout<< "Instance already Exist" <<endl;
  }

  return _instance;
}

void Singleton::p rintsomething (const char* str2print)
{
  cout<< "printer is now working, the sequence:" & lt;<++count<<endl;
  cout<<str2print<<endl;
  cout<< "done\n" <<endl;
}

The main.cpp file code is as follows:

#include "singleton.h"

int main ()
{
  Singleton *t1 = Singleton::getinstance ();
  T1->getinstance ();
  T1->printsomething ("T1");

  Singleton *t2 = Singleton::getinstance ();
  T2->printsomething ("T2");
  return 0;
}

Makefile File:

cc=g++
cflags =-g-o2-wall all

: Make
  singleton singleton:singleton.o\ main.o ${cc}-  
  o Singleton main.o singleton.o Clean

:
  rm-rf singleton rm-f

. *.O:
  $ (CC) $ (CPP.O) cflags-c-o $ <

The effect is as shown in the following illustration:

As you can see, the count for the print order count is continuous and there is only one print device in the system.

I hope this article will help you with the C + + program design.