resize vector element of a struct - segv - c++

Question

I am trying to resize a vector element of a structure and it causes segv. But when I did it individually for some small struct it worked fine. I am curious to know how it allocates memory to structure in which there is a vector element that could be resized. The below comment line causes segv in first iteration (type_index = 0).
Structure:-
struct thread_data {
dbPointer_t pObj;
dbObjId_t objId;
dbObjTypeId_t type;
dbObjId_t topCellId;
dbIteratorId_t objsIterId;
int precision;
int64_t shape_objs;
vector<vector<vector<PL_trp_header_t *> > > ps_hdrs;
int pool;
int num_layers;
int to_cell_id;
};
Below is the snippet of code:-
thread_data *t_data[types_length];
for(int type_index=0; type_index < types_length; ++type_index) {
t_data[type_index] = (thread_data*)malloc(sizeof(thread_data));
t_data[type_index]->pObj = NULL;
t_data[type_index]->objId = objId;
t_data[type_index]->type = shape_types[type_index];
t_data[type_index]->topCellId = topCellId;
t_data[type_index]->objsIterId = objsIterId;
t_data[type_index]->precision = nparams.unit_precision;
t_data[type_index]->shape_objs = 0;
t_data[type_index]->ps_hdrs.resize(num_layers); //this line causes segv
t_data[type_index]->pool = pool;
t_data[type_index]->num_layers = num_layers;
t_data[type_index]->to_cell_id = tocell_id;
for (int num = 0; num < num_layers; num++) {
t_data[type_index]->ps_hdrs[num].resize(index_limit);
for (int rows = 0; rows < index_limit; rows++)
t_data[type_index]->ps_hdrs[num][rows].resize(index_limit);
}
for(int i = 0; i < num_layers; i++) {
for (int rows = 0; rows < index_limit; rows++) {
for (int cols = 0; cols < index_limit; cols++) {
t_data[type_index]->ps_hdrs[i][rows][cols] = alloc_hdr(pool);
}
}
}
printf("In main: creating thread %d \n", type_index);
rc_thread = pthread_create(&threads[type_index], NULL, thread_fn, (void *) &t_data[type_index]);
if (rc_thread){
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
free(t_data[type_index]);
}

Answer 1

I think you are allocating your data with malloc. In this case no constructors for your objects and theier members are called. This works with PODs but not with classes like vector. In the line with the error you try to access some unitialised memory like an vector. Try new and delete instead of mallac and free to solve this isue.