Allocating a pointer

[hockymot2008_2009]

I have a pointer to a struct. In C++ I can allocate and deallocate it but in C#, I can't. Could you give me a solution plz !

[hockymot2008_2009]

For example I have a struct like this : public unsafe struct V { unsafe public V* backpointer; }; When I declare : V n = new V(); n.backpointer = &x in a loop then the previous value of backpointer changed. Could you plz help me ?

modified on Sunday, October 5, 2008 9:50 PM

[hockymot2008_2009]

I think that the garbage collector deallocated the memory. How can we stop it plz ?

[Eslam Afifi]

Use the fixed[^] keyword. More about unsafe code[^]. By the way, you don't need a second unsafe keyword inside another unsafe. And you don't need a semicolon after a struct or class declaration.

public unsafe struct V
{
public V* backpointer; //you don't need another unsafe keyword
}

Eslam Afifi

[Guffa]

In .NET a struct is always a value type, it's not like in C++ where a struct is either a reference type or a value type depending on how it's used. You should use a class, not a struct.

Despite everything, the person most likely to be fooling you next is yourself.

[Guffa]

hockymot2008_2009 wrote:

V n = new V();

That doesn't do what you think that it does. As the struct is a value type, you are not allocating memory for an object, you are just creating a struct value. The value is assigned to the struct n, and will overwrite the previous value in the struct. Is there any reason why you are trying to use structs instead of classes and pointers instead of references?

Despite everything, the person most likely to be fooling you next is yourself.

[Guffa]

hockymot2008_2009 wrote:

I think that the garbage collector deallocated the memory.

No, it didn't, as you never allocated any memory from the heap.

Despite everything, the person most likely to be fooling you next is yourself.

[hockymot2008_2009]

Thanks for your replies :D