Re: Returning Char array/pointer? Continuing of thread I am confused with these concepts.

From:
David Wilkinson <no-reply@effisols.com>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 11 Feb 2008 16:43:45 -0500
Message-ID:
<OSL9vcPbIHA.1208@TK2MSFTNGP05.phx.gbl>
rockdale wrote:

Thanks for the reply.

I still have one thing:

2. Whne you pass by reference, you are indeed calling malloc (or new)
on the
original pointer (that is what pass by reference does for you).

By say that, did you mean I do not need to call delete in the caller?
Or did you mean I do not need to do the new inside my function?

        aDestArr = new char[lngFileSize+1];

--------------------
//Calling the func
char* myByte;
long lngSize = 0;

lngSize = readFileToByteArray("myFileName", myByte);

//Do I need to delete myByte here?

---------------------
my function

long ReadFileToByteArray(char const* aSrcFile, char* aDestArr){
        long lngFileSize = 0;
        int intBeenRead = 0;
        ifstream in;

        in.open(aSrcFile, ios::in| ios::binary | ios::ate);
        if(in.is_open()||in.bad())
        {
                lngFileSize = in.tellg();
        }else{
                throw exception("could not open input file"); // could
not open in
file
                return 0;
        }

        aDestArr = new char[lngFileSize+1];
        in.seekg(0,ios::beg);
        in.read(aDestArr, lngFileSize);
        aDestArr[lngFileSize] = '\0';
        in.close();
        return lngFileSize;

}


Rockdale:

You need to think about what you are doing. In the above you did not pass the
pointer by reference, so the caller cannot retrieve the information (because the
original pointer myByte is not altered. The function must receive the pointer by
reference in order to make this approach work.

You must also call delete [] in the caller (for every new[] there must be a
delete[]).

--
David Wilkinson
Visual C++ MVP

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