Can anybody help me about the memory leak

[Ge Chunyuan]

Eg. we have the class hiaerarchy Point inherit Point3D

class Point
{
public:
Point(int a=0,char* b=0):x(a),y(b){}
private:
int x;
char* y;
};

class Point3D: public Point
{
public:
Point3D(char*c=0):z(c){}
private:
char* z;
}

Once we instatiate an array like this:
Point* pPointArray = new Point3D[10];
delete[] pPointArray;

why this will cause memory leak?
will delete recursively invoke Point3D's destructor.

Thanks indeed
Ge Chunyuan

[Neelesh Bodas]

On Jul 24, 9:16 am, Ge Chunyuan <[e-mail]:

Eg. we have the class hiaerarchy Point inherit Point3D

class Point
{
public:
Point(int a=0,char* b=0):x(a),y(b){}
private:
int x;
char* y;

};

class Point3D: public Point
{
public:
Point3D(char*c=0):z(c){}
private:
char* z;

}

missing semicolon

>
Once we instatiate an array like this:
Point* pPointArray = new Point3D[10];
delete[] pPointArray;

why this will cause memory leak?
will delete recursively invoke Point3D's destructor.

1. The base class destructor must be virtual if you wish to delete a
derived class object through the base class pointer.

2. Deleting array of derived class objects through base class pointer
is undefined.

3. 'Never Treat Arrays Polymporphically' : More Effective C++ (Point
3).

-N

[jg]

On Jul 23, 9:16 pm, Ge Chunyuan <[e-mail]:

Eg. we have the class hiaerarchy Point inherit Point3D

class Point
{
public:
Point(int a=0,char* b=0):x(a),y(b){}
private:
int x;
char* y;

};

class Point3D: public Point
{
public:
Point3D(char*c=0):z(c){}
private:
char* z;

}

Once we instatiate an array like this:
Point* pPointArray = new Point3D[10];
delete[] pPointArray;

why this will cause memory leak?
will delete recursively invoke Point3D's destructor.

Thanks indeed
Ge Chunyuan

To declare an array of Point3D, the default ctor Point3D::Point3D()
as well as Point::Point() must be defined.

Can your code be compiled successfully ?

JG

[Neelesh Bodas]

On Jul 24, 10:00 am, jg <[e-mail]:

On Jul 23, 9:16 pm, Ge Chunyuan <[e-mail]:

Eg. we have the class hiaerarchy Point inherit Point3D

class Point
{
public:
Point(int a=0,char* b=0):x(a),y(b){}
private:
int x;
char* y;

};

class Point3D: public Point
{
public:
Point3D(char*c=0):z(c){}
private:
char* z;

}

Once we instatiate an array like this:
Point* pPointArray = new Point3D[10];
delete[] pPointArray;

why this will cause memory leak?
will delete recursively invoke Point3D's destructor.

Thanks indeed
Ge Chunyuan

To declare an array of Point3D, the default ctor Point3D::Point3D()
as well as Point::Point() must be defined.

Point::point(int =0, char* = 0) can act as Point::Point() since all
its arguments have default values.

Can your code be compiled successfully ?

It cannot, simply because there is a missing semicolon after
definition of Point3D. Otherwise it does.

JG

-N

[1983ddd]

On Jul 24, 1:53 pm, Neelesh Bodas <[e-mail]:

On Jul 24, 10:00 am, jg <[e-mail]:

On Jul 23, 9:16 pm, Ge Chunyuan <[e-mail]:

Eg. we have the class hiaerarchy Point inherit Point3D

class Point
{
public:
Point(int a=0,char* b=0):x(a),y(b){}
private:
int x;
char* y;

};

class Point3D: public Point
{
public:
Point3D(char*c=0):z(c){}
private:
char* z;

}

Once we instatiate an array like this:
Point* pPointArray = new Point3D[10];
delete[] pPointArray;

why this will cause memory leak?
will delete recursively invoke Point3D's destructor.

Thanks indeed
Ge Chunyuan

To declare an array of Point3D, the default ctor Point3D::Point3D()
as well as Point::Point() must be defined.

Point::point(int =0, char* = 0) can act as Point::Point() since all
its arguments have default values.

Can your code be compiled successfully ?

It cannot, simply because there is a missing semicolon after
definition of Point3D. Otherwise it does.

You are so funny.

JG

-N

[1983ddd]

On Jul 24, 2:09 pm, "[e-mail]" <[e-mail]:

On Jul 24, 1:53 pm, Neelesh Bodas <[e-mail]:

On Jul 24, 10:00 am, jg <[e-mail]:

On Jul 23, 9:16 pm, Ge Chunyuan <[e-mail]:

Eg. we have the class hiaerarchy Point inherit Point3D

class Point
{
public:
Point(int a=0,char* b=0):x(a),y(b){}
private:
int x;
char* y;

};

class Point3D: public Point
{
public:
Point3D(char*c=0):z(c){}
private:
char* z;

}

Once we instatiate an array like this:
Point* pPointArray = new Point3D[10];
delete[] pPointArray;

why this will cause memory leak?
will delete recursively invoke Point3D's destructor.

Thanks indeed
Ge Chunyuan

To declare an array of Point3D, the default ctor Point3D::Point3D()
as well as Point::Point() must be defined.

Point::point(int =0, char* = 0) can act as Point::Point() since all
its arguments have default values.

Can your code be compiled successfully ?

It cannot, simply because there is a missing semicolon after
definition of Point3D. Otherwise it does.

You are so funny.

JG

-N

But I want to know where it will leak? I have no found any new
operation except Point = new ...
Forgive me my shallow about memory leak. Thank you.

[James Kanze]

On Jul 24, 10:16 am, "Alf P. Steinbach" <[e-mail]:

* Ge Chunyuan:
and I believe the C++ committee pages link to
the latest draft (which has many things not yet officially standard).

I'm not sure off hand if you can access this without being a
member or not. But if you can, it's probably the better
solution. For the most, the changes are marked, so you can
still see what the official standard said. (This is not
necessarily true when the change is the introduction of an
entire new section, and there's no indication, for example, that
§23.4 doesn't exist at all in the currently official version.)

--
James Kanze (GABI Software) email:ja*********@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, [phone]

[Pete Becker]

On 2007-07-24 09:18:26 -0400, James Kanze <ja*********@gmail.comsaid:

On Jul 24, 10:16 am, "Alf P. Steinbach" <[e-mail]:

>* Ge Chunyuan:
and I believe the C++ committee pages link to
the latest draft (which has many things not yet officially standard).

I'm not sure off hand if you can access this without being a
member or not. But if you can, it's probably the better
solution. For the most, the changes are marked, so you can
still see what the official standard said. (This is not
necessarily true when the change is the introduction of an
entire new section, and there's no indication, for example, that
§23.4 doesn't exist at all in the currently official version.)

The change bars show changes from the previous draft, not from the
current standard. That includes new and removed sections, but, as with
all the other changes, only for the first revision where the change
occurred.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)