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Freeing Char Array memory

Posted on 2004-09-20
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Last Modified: 2010-04-01
I have the following code:

char *bodybuf=0; unsigned int bodysize=0;
IStream *istream;
hr = imsg->OpenProperty(PR_BODY, &IID_IStream, STGM_READ, 0, (IUnknown**)&istream);
if (hr==S_OK)
{
                  STATSTG stg = {0};
                  hr = istream->Stat(&stg,STATFLAG_NONAME);
                            if (hr==S_OK)
                              {
                        bodysize = stg.cbSize.LowPart; // won't bother checking for >2gb messages!
                        bodybuf = new char[bodysize+1];
                        ULONG red;
                        hr = istream->Read(bodybuf, bodysize, &red);
                        if (hr!=S_OK)
                                  bodysize=0;
                        else if (red<bodysize)
                                  bodysize=red;
                                  bodybuf[bodysize]=0;
                        }
                        istream->Release();
                  }

in the event that the amount red from the IStream (red) is less than the amount allocated (bodysize + 1), the string will be null terminated by the call to bodysize = red; and then bodybuf[bodysize] = 0;  

however, when I call delete [] bodybuf, will this leak memory?  If so, what is the proper way to handle this?
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Question by:jjacksn
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6 Comments
 
LVL 55

Accepted Solution

by:
Jaime Olivares earned 300 total points
ID: 12107399
delete operator will not evaluate the lenght of your string, or where is a terminating null character located, it will free the same memory amount as allocated in new char[bodysize+1], so don't worry about this.
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Assisted Solution

by:Sys_Prog
Sys_Prog earned 200 total points
ID: 12107662
Though there wont be any problem deleting, as jaime said, delete just deletes the memory allocated by new

It does not look out for lengt og string or NULL charater etc etc

Hwever, why dont u allocate only that much memory as needed

THus, after u come to know that I need red aamount of mmoery, allocate that much.......that wuld not waste your memory

Amit
0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 12107760
Since IStream don't has a method to know how many bytes are pending, I think jjacksn implementation is ok. There is no (little) memory waste because once processed, buffer will be deleted.
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LVL 10

Expert Comment

by:Sys_Prog
ID: 12107824
I think once its kknow that REad has succeded, then red wuld contain the size. Hence that can be used to allocaate

amit
0
 
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Author Comment

by:jjacksn
ID: 12108792
but the read needs the allocated buffer.
0
 
LVL 10

Expert Comment

by:Sys_Prog
ID: 12110940
ohh...yes....i am sorry...didnt notice that
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