Re: Error while deallocating memory

[Frank Schaeckermann]

Boris Epshteyn wrote:
Hi,

I have an interesting problem. I am allocating an array of strings.
This array is filled from the database and then used for populating
pop-up list. When program is ran, list pops up fine, item gets
selected, but when I tap on the trigger again I get:
"just read from the ... which is the reserved field of the
frmControlObj," bla-bla-bla.
If my clean-up portion of the code is commented out, everything runs
fine, but creates memory leaks. Clean-up portion is:
for (i = numRec - 1; i >= 0; i--)
{
MemPtrFree(programsArray[i]);
}
MemPtrFree(programsArray);
I would appreciate any ideas why it is happening. The code is bellow:

static Boolean frmNewM_trProg_OnSelect(EventPtr event)
{
        ListType *list = GetObjectPtr(lstPrograms);
        Int16 listItem, cardNo;
        UInt32 numRec = 0;
        Err err;
        char** programsArray;
        MemHandle record;
        LocalID progLocID;
        Program* prog;
        int i;
        MemPtr ptr;
        err = DmOpenDatabaseInfo(progDB, &progLocID, NULL, NULL,&cardNo, NULL);
        if (progLocID != 0)
        {
           err = DmDatabaseSize(cardNo, progLocID, &numRec, NULL, NULL);
        }
        programsArray = (char**)MemPtrNew(numRec * sizeof(char*));
        
        for (i = 0; i < numRec; i++)
        {               
           record = DmQueryRecord(progDB, (UInt16)i);
           if (record)
           {
              prog = (Program*)MemHandleLock(record);
              ptr = &prog->programName;
              programsArray[i] = (char*)MemPtrNew(StrLen(ptr) + 1 );
              StrCopy(programsArray[i], ptr);
              MemHandleUnlock(record);
           }
        }
        LstSetListChoices(list, programsArray, numRec);
        listItem = LstPopupList(list); 
        
        if(listItem != -1)
        {
                ControlType *trg = GetObjectPtr(trProg);
                CtlSetLabel(trg, programsArray[listItem]);
Boris,
is CtlSetLabel actually copying the string or just storing a reference 
to it (can't look it up right now)? If it stores just a reference to the 
string you can't free the memory before the label is destroyed
        }
        for (i = numRec - 1; i >= 0; i--)
        {
                MemPtrFree(programsArray[i]);
        }
        MemPtrFree(programsArray);
        return true;
}
  



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