CODEWITHSUNDEEP
c++cmemory-management
cppb
cppb

Reputation: 2409

how to check if memory is allocated using malloc or new

I am dealing with some legacy C/C++ code where memory is allocated using malloc as well as using new. I want to create a generalized wrapper function to deallocate the memory using either free or delete [] , depending on how it is allocated.

Is there a way to determine how memory is allocated ? Here is a pseudo code. 

double *x;
double *y;
x = (double *) malloc(size);
y = new double [size]

doSomething();
deallocateMemory(x, y);

I want deallocateMemory to determine whether to call free or delete [] . Any help would be appreciated.

Upvotes: 3

Views: 2203

Answers (3)

DevSolar
DevSolar

Reputation: 70243

You can implement malloc() yourself instead of using the implementation provided by the standard library. You can also overload the operators new and delete. Nothing keeps you from adding your own bookkeeping to either of these implementations, so yes, this is perfectly possible.

Is it recommended? No it isn't.

This smacks of an attempt at implementing garbage collection. If this is true, you are looking at C++ from the wrong way. C++ does have its cleanup facility, which is its destructors. There are ready-made implementations of pointer containers, which in their destructors clean up the allocated memory. Others have mentioned them, and I don't copy-paste from other people's answers.

Upvotes: 6

masoud
masoud

Reputation: 56479

You want to write

a generalized wrapper function to deallocate the memory

then you need to write

a generalized wrapper function to allocate the memory

and, it is not recommended at all. Try to make your goal clean. If you have to deal with malloc/free pointer in some part of your code and you can not modify malloc parts, then try not to mix that part with your new/delete part.

Otherwise, you have no standard way to determine what allocation method is used for a pointer.

Upvotes: 2

Cheers and hth. - Alf
Cheers and hth. - Alf

Reputation: 145204

Wrap the raw pointers in appropriate smart pointers (e.g. std::unique_ptr, std::shared_ptr) as soon as you take ownership.

Also, order a nine-tail cat and flog the persons responsible for the mess.

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Upvotes: 6

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