I am implementing a vector in C and am having trouble with the delete function. 

1) here is my vector struct: 

typedef struct {
  void* elems;
  int elemSize;
  int logLength;
  int allocLength;
  VectorFreeFunction vfree;
} vector;

2) here is the function from which i call the delete function (in a test file):
static void TestInsertDelete(vector *alphabet)
{
  char ch = '-';
  int i;
  for (i = 3; i <= VectorLength(alphabet); i += 4) // Insert dash every 4th char 
    VectorInsert(alphabet, &ch, i);
  fprintf(stdout, "\nAfter insert dashes: ");
  VectorMap(alphabet, PrintChar, stdout);
  
  for (i = 3; i < VectorLength(alphabet); i += 3) // Delete every 4th char 
    VectorDelete(alphabet, i);
  fprintf(stdout, "\nAfter deleting dashes: ");
  VectorMap(alphabet, PrintChar, stdout);
    
  ch = '!';
  VectorInsert(alphabet, &ch, VectorLength(alphabet));
  VectorDelete(alphabet, VectorLength(alphabet) - 1);
  fprintf(stdout, "\nAfter adding and deleting to very end: ");
  VectorMap(alphabet, PrintChar, stdout);
}

3) Finally, here is my vector delete implementation that is causing an error (an "abort (core dumped)" error, it also says that there is an invalid pointer):

//VectorDelete will use the client-supplied free function to free the
//actual memory pointed to by the elements in the vector.
void VectorDelete(vector *v, int position)
{
  fprintf(stdout,"gets  to delete \n");
  assert (position >=0);
  assert (position <= v->logLength-1);
  assert (v != NULL);
  void* movept = (char*) v-> elems + position * v->elemSize;
  assert (movept != NULL);
  free(movept);
  if(v->vfree == NULL)free(movept);
  else v->vfree(movept);
  memmove(movept, (char*) movept + v-> elemSize, v-> logLength* v-> elemSize - position*v->
   elemSize);
  v->logLength--;
}


ERROR GENERATED: 
*** glibc detected *** ./vector-test: free(): invalid pointer: 0x0804c00b ***
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6[0xb7eaf7cd]
/lib/tls/i686/cmov/libc.so.6(cfree+0x90)[0xb7eb2e30]
./vector-test[0x80497f3]
./vector-test[0x8048a6c]
./vector-test[0x8048c7c]
./vector-test[0x80492f9]
/lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xdc)[0xb7e5debc]
./vector-test[0x8048601]
======= Memory map: ========
08048000-0804b000 r-xp 00000000 00:13 1354564242  /afs/ir.stanford.edu/users/l/i/lizb1/myassn3/assn-3-vector-hashset/vector-test
0804b000-0804c000 rw-p 00002000 00:13 1354564242  /afs/ir.stanford.edu/users/l/i/lizb1/myassn3/assn-3-vector-hashset/vector-test
0804c000-0806d000 rw-p 0804c000 00:00 0          [heap]
b7d00000-b7d21000 rw-p b7d00000 00:00 0 
b7d21000-b7e00000 ---p b7d21000 00:00 0 
b7e47000-b7e48000 rw-p b7e47000 00:00 0 
b7e48000-b7f83000 r-xp 00000000 08:01 1176036    /lib/tls/i686/cmov/libc-2.5.so
b7f83000-b7f84000 r--p 0013b000 08:01 1176036    /lib/tls/i686/cmov/libc-2.5.so
b7f84000-b7f86000 rw-p 0013c000 08:01 1176036    /lib/tls/i686/cmov/libc-2.5.so
b7f86000-b7f89000 rw-p b7f86000 00:00 0 
b7f89000-b7f94000 r-xp 00000000 08:01 1172800    /lib/libgcc_s.so.1
b7f94000-b7f95000 rw-p 0000a000 08:01 1172800    /lib/libgcc_s.so.1
b7f95000-b7f98000 rw-p b7f95000 00:00 0 
b7f98000-b7fb1000 r-xp 00000000 08:01 1172757    /lib/ld-2.5.so
b7fb1000-b7fb3000 rw-p 00019000 08:01 1172757    /lib/ld-2.5.so
bffb2000-bffc8000 rw-p bffb2000 00:00 0          [stack]
ffffe000-fffff000 r-xp 00000000 00:00 0          [vdso]
Abort (core dumped)
pod8:~/myassn3/assn-3-vector-hashset>

for (i = 3; i < VectorLength(alphabet); i += 3) // Delete every 4th char

  void* movept = (char*) v-> elems + position * v->elemSize;
  assert (movept != NULL);
  free(movept);
  if(v->vfree == NULL)free(movept);
  else v->vfree(movept);
  memmove(movept, (char*) movept + v-> elemSize, v-> logLength* v-> elemSize - position*v->
   elemSize);
  v->logLength--;

  void* movept = (char*) v-> elems + position * v->elemSize;

 free(movept);

//VectorDelete will use the client-supplied free function to free the
//actual memory pointed to by the elements in the vector.
void VectorDelete(vector *v, int position)
{
  fprintf(stdout,"\n gets  to delete \n");
  assert (position >=0);
  assert (position <= v->logLength-1);
  assert (v->elems != NULL);
  v-> elems = (char*) v-> elems + position* v-> elemSize;
  assert (v-> elems != NULL);
  fprintf(stdout,"ok gets to the place \n");
  if(v->vfree == NULL) free (v->elems);
  else v->vfree (v-> elems);
  // void* movept = (char*) v-> elems + position * v->elemSize;
  // assert (movept != NULL);
  //there is some error with the pointer itself, not what it does 
  //fprintf(stdout, "\n woot");
  //if(v->vfree == NULL)free(movept);
  //  else v->vfree(movept);
  void* movept = v-> elems;
   memmove(movept, (char*) movept + v-> elemSize, v-> logLength* v-> elemSize - position*v->
   elemSize);
  if(v-> logLength > 0)v->logLength--;
}

v-> elems = (char*) v-> elems + position* v-> elemSize;
assert (v-> elems != NULL);
fprintf(stdout,"ok gets to the place \n");
if(v->vfree == NULL) free (v->elems);

void VectorNew(vector *v, int elemSize, VectorFreeFunction freeFn, int initialAllocation)
{
  //purpose of vect free function?
  assert(elemSize >  0);
  v->logLength = 0;
   if(initialAllocation ==0) initialAllocation = INT_ALL_SIZE;
  v->allocLength = initialAllocation;
  v->elemSize = elemSize;
  v->elems = malloc (v-> allocLength * v-> elemSize);
  assert (v->elems != NULL);
  fprintf(stdout,"done calling vector new\n");
}