Re: another memory leak, weird`

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"Vivienne" <zhoudan.bupt@xxxxxxxxx> wrote in message
news:1190167122.240652.254120@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
I test the below function. memory leak occured ...

void testleak{
std::string a;
std::cin >> a;
_CrtDumpMemoryLeaks();

}

when I input a few charactors, like 10 charactors, no memory leak
occured here. but when I input more charactors, like 20, memory leak
occured!
why?

The string 'a' has not yet gone out of scope and has not been destroyed
by the time you call _CrtDumpMemoryLeaks. Any memory it has allocated on
the heap is (incorrectly) reported as a leak.

It so happens that a particular implementation of std::string you are
using employs so called small string optimization: strings shorter than
a certain limit are stored directly inside the string object itself,
thus not requiring a heap allocation. Memory for longer strings is still
allocated on the heap. That's why you see a false leak report for long
strings but not for short ones.
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925


.

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