Segmentation fault upon calling delete

Question

gdb backtrace:

#0  0x0040cea9 in free () from /lib/tls/i686/cmov/libc.so.6
#1  0x0033c741 in operator delete(void*) () from /usr/lib/libstdc++.so.6
#2  0x080654b6 in mesh::calculateMeanNormalsPerVertex (this=0x807d684)
    at /home/brent/Desktop/protCAD/src/math/mesh.cc:230
#3  0x0805638f in buildCubes (argc=4, argv=0xbffff3e4)
    at /home/brent/Desktop/protCAD/src/driver/executeCubes.cc:163
#4  main (argc=4, argv=0xbffff3e4)
    at /home/brent/Desktop/protCAD/src/driver/executeCubes.cc:297

Declaration and delete call in mesh.cc:

vector<vector<int> > faceIndicesPerVertex (vertexArray.size());
...
delete[] &faceIndicesPerVertex;    //line 230

I'm sure I have this wrong, but I've tried a few different ways of calling delete there, but none seem to compile except the above. What's the problem?

score 7 · Accepted Answer · answered Dec 07 '11 at 08:15

You don't need to delete any stack-allocated object, stack-allocated vector object included - it will be destroyed and its memory will be reclaimed when the object goes out of scope. Trying to delete a stack-allocated object leads to undefined behavior (crash in your case).

score 3 · Answer 2 · answered Dec 07 '11 at 08:16

First of all, faceIndicesPerVertex is not an array, so you cant call delete[].

And second, faceIndicesPerVertex is a local variable. This means it's on the stack. This means you can't use delete on it.

Only use delete on objects you allocate in the heap with new.

score 2 · Answer 3 · answered Dec 07 '11 at 08:15

2

You don't have to call delete[]. It's automatically allocated variable/container, it will be automatically destroyed/freed memory.

Call delete when you call new and vise versa. The same for new[] and delete[].

answered Dec 07 '11 at 08:15

Kiril Kirov

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score 1 · Answer 4 · answered Dec 07 '11 at 08:15

1

faceIndicesPerVertex is not a pointer, it was allocated on stack. You can't delete it, and you don't have to.

answered Dec 07 '11 at 08:15

Igor

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score 1 · Answer 5 · edited Aug 10 '14 at 15:39

1

faceIndicesPerVertex is not a pointer, so delete[] is not required.
faceIndicesPerVertex is a vector so delete[] will not even work.

edited Aug 10 '14 at 15:39

Unihedron

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answered Dec 07 '11 at 08:17

Dennis

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score 1 · Answer 6 · answered Dec 07 '11 at 08:57

As far as I know, delete is used only for deallocating memory from the heap. You cannot delete stack allocated memory using delete. As a general rule, delete memory only if you dynamically allocated it using new. I also had some problems with the usage of new/delete. If you follow the general rule of using new and delete in pairs, you should be fine.

Segmentation fault upon calling delete

6 Answers6