Allocating and freeing memory (, )

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Hello all,

Let's assume that I have an array of structures, where the size is determined dynamically:

MIDL

myStruct *pMyStruct = new myStruct[structSize];

and let's assume that myStruct has a member which is a pointer to an array of strings:

MIDL

string *pMyList;

Somewhere in the code I allocate a temporary array of strings:

C#

string *pTempList = new string[listSize];

and later in the code I assign that temporary array to the instances of myStruct

MIDL

pMyStruct[i].pMyList = pTempList;

The question is how I should free the memory once I am done with the instances of myStruct.
Do I have to make a loop over [structSize] where I free pMylist for every instance of myStruct, then free pMyStruct (and then free pTempList)?

Best regards,
Enrique

Posted 28-Nov-10 22:50pm

Member 3605757

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Alain Rist · Accepted Answer · 2010-11-28T23:46:00

Hi Enrique,

You don't have the same interrogation about your std::strings because you know that they have their own internal memory management.

Similarly the Standard C++ Library provides std::vector<> with internal memory management.

If you used it instead of C arrays your question would look like:
.. let's assume that myStruct has a member which is ~~a pointer to an array of strings~~ a vector of strings:

struct myStruct
{
	std::vector<std::string> MyList;
};

Let's assume that I have ~~an array~~ a vector of structures, where the size is determined dynamically:

std::vector<myStruct> MyStruct(structSize);

Somewhere in the code I allocate a temporary ~~array~~ vector of strings:

std::vector<std::string> TempList(listSize);

and later in the code I assign that temporary ~~array~~ vector to the instances of myStruct

MyStruct[i].MyList = TempList;

The question is how I should free the memory once I am done with the instances of myStruct.

The answer would be: You have nothing to do, all memory is deallocated in the objects destructors which are called when they get out of scope.

cheers,
AR