the leak of the memory in c++ 03

The Leak of the Memory in C++

    In this chaper I will introduce a new smart pointer which is scoped_ptr;
It likes auto_ptr but better. When peopel use auto_ptr, sometimes they forget
that auto_ptr alread is empty, like this;
  

 auto_ptr<Person> p1(new Person);    auto_ptr<Person> p2 = p1;    cout << p1->name() << endl;

    In above situation, p1 is empty pointer after it gives pointee to p2. It
will produce some error.
    But scoped_ptr can't give pointee to any pointer, so it will be better and
safer in some cases.
    Now I'll introduce some special pattern to you, I say special, because in
normal cases, it just used in C++; In articles which I wrote before, I avoided
to use operator of delete, but I still use new operator, in this article I'll
introduce method which can help us to avoid use new operator.
    Now let us welcome our pattern: PIMPL, it means Pointer to Implement. It
looks like below.

PersonImpl.h

class PersonImpl{public:    PersonImpl()    {        cout << "I'm constructed" << endl;    }    ~PersonImpl()    {        cout << "I'm destructed!" << endl;    }private:    int age_;    string name_;public:    const string& getName()const    {        return name_;    }    void setName(const string& name)    {        name_ = name;    }    int getAge()    {        return age_;    }    void setAge(int age)    {        age_ = age;    }};

Person.h

using namespace std;using namespace boost;class Person{public:    Person() :        personPtr_(new PersonImpl)        {}    ~Person()    {    };private:    scoped_ptr<PersonImpl> personPtr_;public:    int getAge()    {        return personPtr_->getAge();    }    void setAge(int age)    {        personPtr_->setAge(age);    }    const string& getName()const    {        return personPtr_->getName();    }    void setName(const string& name)    {        personPtr_->setName(name);    }};

main.cpp

using namespace std;using namespace boost;int main(int,char**){    Person person;    return 0;}

    In above code, I did not implement Person directly, instead of a smart
pointer which point a class which implement Person. So we can use class Person
just like I use it in main function without new neither delete operators.