Using "new"

[BeerFizz]

I am reading records from a very large file. Approx 15 MB.
I am using "new" to allocate memory for the structure each time I read a record. I test for null.

This works for a smaller file, in the 1MB range. But when I tried with a larger file, it appeared to hang (loop), or something.

Am I runing out of heap space? Is there away to allocate more memory/heap? Is there a different way of doing this all together?

Thanks
phil

 

[Salem]

Depends what you're doing with that memory.

If you're building a linked list of records, and searching from the head element each time, then yes, performance will tail off very rapidly as more records are added to the list.

--

 

[Skute]

Are you using delete afterwards to free the memory?

Skute

"There are 10 types of people in this World, those that understand binary, and those that don't!"

 

[PerFnurt]

>Is there a different way of doing this all together?

Consider if storing the records in an array/vector is applicable. Then you could read it all in one go.

/Per

_{"It was a work of art, flawless, sublime. A triumph equaled only by its monumental failure."}

 

[BeerFizz]

OK.

Yes I am building a linked list.

Yes, I do use "free" and walk down the list freeing each cell in the list.

This worked fine with smaller files, with a large file it appears to hang. I understand the performance issues, however, in this case, it hangs during the creation of the linked list. I can't tell how far it got.

Are there limitations to the size of the heap? Any other ideas?

All help appreciated.

Thanks
phil

 

[PerFnurt]

free"?!?!?

The complement of new is delete.



/Per

_{"It was a work of art, flawless, sublime. A triumph equaled only by its monumental failure."}

 

[BeerFizz]

pBI = pStartBI;
while (pBI->NextBI != NULL) {
p1BI = pBI;
pBI = pBI->NextBI;
delete p1BI;
}
delete pBI;

right, I am actually using delete.

 

[BeerFizz]

Below is the code I am using to create the linked list. There would be, when complete, about 330,000 cells in the list. BatchItem is a struct with ints and CStrings. I am assuming the compiler knows what size the struct is...

pNxtBI = new BatchItem;
if (pNxtBI == NULL) {
MessageBox("New failed to allocate memory. Fatal Error",
"Memory Error", MB_ICONEXCLAMATION );
return;
}
pNxtBI->NextBI = NULL;
pBI->NextBI = pNxtBI;
pBI = pNxtBI;

 

[PerFnurt]

To make things simple may I sugest you use the collections already provided by STL? If you're determined to use a linked list, there already is one implemented...see docs on std::list





/Per

_{"It was a work of art, flawless, sublime. A triumph equaled only by its monumental failure."}

 

[BeerFizz]

Thanks PerFnurt and thanks to everyone else who responded.

Phil