Valgrind BBV, Быстрый старт

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Memcheck: a memory error detector
4.2.4. Illegal frees
For example:
Invalid free()
at 0x4004FFDF: free (vg_clientmalloc.c:577)
by 0x80484C7: main (tests/doublefree.c:10)
Address 0x3807F7B4 is 0 bytes inside a block of size 177 free’d
at 0x4004FFDF: free (vg_clientmalloc.c:577)
by 0x80484C7: main (tests/doublefree.c:10)
Memcheck keeps track of the blocks allocated by your program with malloc / new , so it can know exactly whether
or not the argument to free / delete is legitimate or not. Here, this test program has freed the same block twice.
As with the illegal read/write errors, Memcheck attempts to make sense of the address freed. If, as here, the address
is one which has previously been freed, you wil be told that -- making duplicate frees of the same block easy to spot.
You will also get this message if you try to free a pointer that doesn’t point to the start of a heap block.
4.2.5. When a heap block is freed with an inappropriate
deallocation function
In the following example, a block allocated with
new[]
has wrongly been deallocated with
free
:
Mismatched free() / delete / delete []
at 0x40043249: free (vg_clientfuncs.c:171)
by 0x4102BB4E: QGArray::~QGArray(void) (tools/qgarray.cpp:149)
by 0x4C261C41: PptDoc::~PptDoc(void) (include/qmemarray.h:60)
by 0x4C261F0E: PptXml::~PptXml(void) (pptxml.cc:44)
Address 0x4BB292A8 is 0 bytes inside a block of size 64 alloc’d
at 0x4004318C: operator new[](unsigned int) (vg_clientfuncs.c:152)
by 0x4C21BC15: KLaola::readSBStream(int) const (klaola.cc:314)
by 0x4C21C155: KLaola::stream(KLaola::OLENode const *) (klaola.cc:416)
by 0x4C21788F: OLEFilter::convert(QCString const &) (olefilter.cc:272)
In
C++
it’s important to deallocate memory in a way compatible with how it was allocated. The deal is:
• If allocated with malloc , calloc , realloc , valloc or memalign , you must deallocate with free .
• If allocated with new , you must deallocate with delete .
• If allocated with
new[]
, you must deallocate with
delete[]
.
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