何时在C ++中删除/取消引用

Question

myObj* var = new myObj;
var = other1;

don't need it anymore

delete var;
var = new myObj;
var = other2;

why can't just dereference instead of deleting and allocating again?

var->other2;

Answer 1

Dereference does not mean delete: http://en.wikipedia.org/wiki/Dereference

I suggest you go through some tutorials on C++, as you seem to have a misunderstanding of what a lot of the vocabulary actually means.

Remember to use google.

Answer 2

Your question is silly, absolutely no offence intended. In other words, you have an underlying confusion here, that cannot be addressed by a simple answer to an inquiry.

I'd strongly recommend you read introductory material to C or C++. The web is full to the brim with excellent lectures, and free e-books. You won't regret it!

Google around :) and maybe, you'll come back to answer your own question in a few days.

Happy coding!

Answer 3

Others have commented on your confusion about terminology. I'll comment on your code.

When you do:

myObj* var = new myObj;
var = other1;

you're creating a memory leak . new myObj allocated memory for a structure, and set var to point there. When you then reassign var , you no longer have a variable pointing to the structure that was allocated. C++ does not have automatic garbage collection, so this memory is no longer accessible, but you also don't have a variable that you can use with delete to reclaim it.

var = other1 reassigns the pointer, it does not copy the contents; if you want to copy structures, you must write:

*var = *other1;

When you then do:

delete var;

you're not deleting the original structure, you're deleting whatever other pointed to. This is only valid if that structure was created using new .

You definitely need to go back and review all your instructional material on pointers in C++.