jhapak
asked on
MFC, Pointers and References
Hello,
Suppose I have two pointers in two different functions and I have a public variable, lets say:
sh1(){
Shape *sh1 = new Shape;
global_sh = sh1;
}
sh2(){
Shape *sh2 = new Shape;
global_sh = sh2;
}
What I want is something to store the address of the point sh1 or sh2 in global_sh. Now somewhere else I declare another pointer "sh3" and say sh3 = global_sh. Now if I say sh3.something() then it should return/call the related object. How can i do it?
Saqib
Suppose I have two pointers in two different functions and I have a public variable, lets say:
sh1(){
Shape *sh1 = new Shape;
global_sh = sh1;
}
sh2(){
Shape *sh2 = new Shape;
global_sh = sh2;
}
What I want is something to store the address of the point sh1 or sh2 in global_sh. Now somewhere else I declare another pointer "sh3" and say sh3 = global_sh. Now if I say sh3.something() then it should return/call the related object. How can i do it?
Saqib
Skongen:
> Shape *sh1 = new Shape;
> global_sh = &sh1;
that's bad, since you take the address of a temporary object. looking at the calling code you probably meant
global_sh = sh1;
Saquib:
With above correction, this would work fine.
However, you have another problem: who is going to delete the shapes?
If you call
sh1();
sh2();
at least the first allocation leaks, because it is not accessible anymore.
To solve that, I'd recommmend using reference counted pointers (e.g. boost::shared_ptr)
> Shape *sh1 = new Shape;
> global_sh = &sh1;
that's bad, since you take the address of a temporary object. looking at the calling code you probably meant
global_sh = sh1;
Saquib:
With above correction, this would work fine.
However, you have another problem: who is going to delete the shapes?
If you call
sh1();
sh2();
at least the first allocation leaks, because it is not accessible anymore.
To solve that, I'd recommmend using reference counted pointers (e.g. boost::shared_ptr)
Sorry about that, looking back at that I see no reasoning in what I did. I assumed he was going to delete global_sh afterwards so I didn't mention anything about freeing the allocated memory once he was done.
ASKER
ok,
I have checked smart pointers, cool thing.
But, my problem is that am using CObList and I have different classes in it. So when ever I put an object on the list it gives me memory leak. Any idea?? How can I delete manually a pointer then?
I have checked smart pointers, cool thing.
But, my problem is that am using CObList and I have different classes in it. So when ever I put an object on the list it gives me memory leak. Any idea?? How can I delete manually a pointer then?
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// ....
sh1(){
Shape *sh1 = new Shape;
global_sh = &sh1;
}
sh2() {
Shape *sh2 = new Shape;
global_sh = &sh2;
}
// ...
Shape *sh3;
sh1();
sh3 = global_sh;
sh3->Something();