What is singleton design pattern

What is singleton design pattern..

Answer / lokesh

Singleton design pattern is a a creational pattern to
dictate how and when objects get created and it's main
purpose is to ensure that a class has only one instance

#define NULL 0

class Singleton
Singleton& operator =(Singleton&);
int nValue;
static Singleton* pSingleton;
static Singleton*Instance()

if(NULL == pSingleton)
pSingleton = new Singleton();
return pSingleton;
void setValue(int val)
nValue = val;
int getValue()
return nValue;
Singleton* Singleton::pSingleton = NULL;

int main(int argc, char* argv[])
Singleton *abc = NULL;

Singleton *xyz = NULL;
Singleton *sss = Singleton::Instance();
return 0;

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