GOOD:保证一个类仅有一个实例,并提供一个访问它的全局访问点
#include <iostream>
#include <string>
using namespace std;
class Singleton
{
private:
int i;
static Singleton *instance;
Singleton(int i)
{
this->i=i;
}
public:
static Singleton *getInstance()
{
return instance;
}
void show()
{
cout<<i<<endl;
}
};
Singleton* Singleton::instance=new Singleton(8899);
class A:public Singleton
{
};
int main()
{
Singleton *s=Singleton::getInstance();
Singleton *s2=A::getInstance();
cout<<(s==s2)<<endl;
return 0;
}