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singlaton in cpp

Desamsetti Sankar answered on April 23, 2023 Popularity 2/10 Helpfulness 1/10

answer singlaton in cpp

singlaton in cpp

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// Implementation of Singleton Class
// in C++
#include <bits/stdc++.h>
using namespace std;
 
class Singleton{
  private:
   
  // member variables
  string name, loves;
     
  static Singleton*
         
  // static pointer which will points
  //to the instance of this class
  instancePtr;
   
  // Default constructor
  Singleton()
  {
  }
   
  public:
   
  // deleting copy constructor
  Singleton(const Singleton& obj)
    = delete;
 
  /*
    getInstance() is a static method that returns an
    instance when it is invoked. It returns the same
    instance if it is invoked more than once as an instance
    of Singleton class is already created. It is static
    because we have to invoke this method without any object
    of Singleton class and static method can be invoked
    without object of class
 
    As constructor is private so we cannot create object of
    Singleton class without a static method as they can be
    called without objects. We have to create an instance of
    this Singleton class by using getInstance() method.
  */
  static Singleton* getInstance()
  {
    // If there is no instance of class
    // then we can create an instance.
    if (instancePtr == NULL)
    {
      // We can access private members
      // within the class.
      instancePtr = new Singleton();
       
      // returning the instance pointer
      return instancePtr;
    }
    else
    {
      // if instancePtr != NULL that means
      // the class already have an instance.
      // So, we are returning that instance
      // and not creating new one.
      return instancePtr;
    }
  }
 
  // sets values of member variables.
  void setValues(string name,
                 string loves)
  {
    this->name = name;
    this->loves = loves;
  }
   
  // prints values of member variables
  void print()
  {
    cout << name << " Loves " <<
            loves << "." << endl;
  }
};
 
// initializing instancePtr with NULL
Singleton* Singleton ::instancePtr = NULL;
 
// Driver code
int main()
{
  Singleton* GeeksForGeeks
      = Singleton ::getInstance();
   
  // setting values of member variables.
  GeeksForGeeks->setValues("Manish",
                           "GeeksForGeeks");
   
  // printing values of member variables.
  GeeksForGeeks ->print();
   
  cout << "Address of GeeksForGeeks: " <<
           GeeksForGeeks << endl;
 
  cout << endl;
 
  Singleton* gfg = Singleton ::getInstance();
   
  // setting values of member variables.
  gfg->setValues("Vartika",
                 "GeeksForGeeks");
   
  // Printing values of member variables.
  gfg->print();
   
  cout << "Address of gfg: " << gfg << endl;
  return 0;
}

Popularity 2/10 Helpfulness 1/10 Language cpp

Source: www.geeksforgeeks.org

Tags: c++

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Contributed on Apr 23 2023

Desamsetti Sankar

0 Answers Avg Quality 2/10

singlaton in cpp

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