Can we have a private constructor ?
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Answer Posted / arun
1. Yes we can make a constructor private. By implementing
this concept we can create a singleTon class.
2. Suppose we have a static method is a class that is used
to create the object of the class by using private
constructor then that member function is named as "Named
Constructor".
3. Using this named constructor concept we can create
SingleTon class as well as normal class.
Example:
class Singleton
{
public:
static Singleton* Instance();
protected:
Singleton();
Singleton(const Singleton&);
Singleton& operator= (const Singleton&);
private:
static Singleton* pinstance;
};
Singleton* Singleton::pinstance = 0;// initialize pointer
Singleton* Singleton::Instance ()
{
if (pinstance == 0) // is it the first call?
{
pinstance = new Singleton; // create sole instance
}
return pinstance; // address of sole instance
}
Singleton::Singleton()
{
//... perform necessary instance initializations
}
Singleton *p1 = Singleton::Instance();
Singleton *p2 = p1->Instance();
Singleton & ref = * Singleton::Instance();
| Is This Answer Correct ? | 25 Yes | 0 No |
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