Question

In my code I have a vector defined:

vector<vector<vector<vector<shared_ptr<foo> > > > > fooBoxes;

I am initializing the vector using:

int BOX_NUM = 12 //this is actually defined elsewhere

fooBoxes.resize(BOX_NUM);
for (int i = 0; i<BOX_NUM; i++){
  fooBoxes[i].resize(BOX_NUM);
  for (int j = 0; j < BOX_NUM; j++){
    fooBoxes[i][j].resize(BOX_NUM);
    for (int k = 0; k < BOX_NUM; k++){
      fooBoxes[i][j][k].resize(0);
    }
  }
}

I suspect that the use of vector is causing me a segmentation fault and I want to replace fooBoxes to be:

vector<vector<vector<set<shared_ptr<foo> > > > > fooBoxes

what do I do in the for loops? simply remove the resize(0) part?

Edit:
This is the output of valgrind in the crash:

==2258== Invalid read of size 8
==2258==    at 0x439237: trans(int) (stl_iterator.h:704)
==2258==    by 0x413B0E: membrane::MCstep(int) (membrane.cpp:490)
==2258==    by 0x402767: main (main.cpp:14)
==2258==  Address 0x7932420 is 8 bytes after a block of size 24 free'd
==2258==    at 0x4A05743: operator delete(void*) (vg_replace_malloc.c:346)
==2258==    by 0x405636: vec::~vec() (valarray_array.h:71)
==2258==    by 0x437D66: trans(int) (transFile.cpp:64)
==2258==    by 0x413B0E: membrane::MCstep(int) (membrane.cpp:490)
==2258==    by 0x402767: main (main.cpp:14)
==2258==
==2258== Invalid read of size 8
==2258==    at 0x439240: trans(int) (stl_vector.h:604)
==2258==    by 0x413B0E: membrane::MCstep(int) (membrane.cpp:490)
==2258==    by 0x402767: main (main.cpp:14)
==2258==  Address 0x111 is not stack'd, malloc'd or (recently) free'd
==2258==
==2258==
==2258== Process terminating with default action of signal 11 (SIGSEGV)
==2258==  Access not within mapped region at address 0x111
==2258==    at 0x439240: trans(int) (stl_vector.h:604)
==2258==    by 0x413B0E: membrane::MCstep(int) (membrane.cpp:490)
==2258==    by 0x402767: main (main.cpp:14)
==2258==  If you believe this happened as a result of a stack
==2258==  overflow in your program's main thread (unlikely but
==2258==  possible), you can try to increase the size of the
==2258==  main thread stack using the --main-stacksize= flag.
==2258==  The main thread stack size used in this run was 10485760.

I believe that the problem is that I’m not careful enough when I try to delete/put a bead into a vector and this is why I want to move to set.

Answer 1

That depends on what you want to achieve. Your code will most definitely compile if you remove fooBoxes[i][j][k].resize(0); since the std::set does not support this function.