QList<QList > question

Hello all,

I'm trying to create a 2-dimensional QList of some structure.

Here's the test code (contents of condition struct isn't important, both stateDWord and zone_id variables are int):

Code:

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taskData td2;
  QList<condition_struct*> *conditions2 = new QList<condition_struct*>;
  QList<QList<condition_struct*>* > *tasks2 = new QList<QList<condition_struct*>* >;
 
  condition_struct *cnd2 = new condition_struct;
  cnd2->stateDWord = 1;
  cnd2->td_current.zone_id = 2;
  conditions2->push_back(cnd2);
  cnd2 = new condition_struct;
  cnd2->stateDWord = 3;
  cnd2->td_current.zone_id = 4;
  conditions2->push_back(cnd2);
 
  tasks2->push_back(conditions2);
 
  cnd2 = new condition_struct;
  cnd2->stateDWord = 5;
  cnd2->td_current.zone_id = 6;
  conditions2->push_back(cnd2);
  cnd2 = new condition_struct;
  cnd2->stateDWord = 7;
  cnd2->td_current.zone_id = 8;
  conditions2->push_back(cnd2);
  cnd2 = new condition_struct;
  cnd2->stateDWord = 9;
  cnd2->td_current.zone_id = 10;
  conditions2->push_back(cnd2);
 
  tasks2->push_back(conditions2);
 
//...
 
  condition_struct *cndCr = new condition_struct;
 
  QList<condition_struct*> *conditionsCr = new QList<condition_struct*>;
 
  printf("tasks2 vector size: %d\n\n",tasks2->size());
  for(QList<QList<condition_struct*>* >::iterator ti0=tasks2->begin();ti0!=tasks2->end();ti0++)
  {
  	printf("conditions2 vector size: %d\n\n", (*ti0)->size());
  	for(QList<condition_struct*>::iterator ci0=(*ti0)->begin();ci0!=(*ti0)->end();ci0++)
  	{
  		cndCr->stateDWord = (*ci0)->stateDWord;
  		cndCr->td_current.zone_id = (*ci0)->td_current.zone_id;
  		printf("stateDWord: %d, zone_id: %d\n",cndCr->stateDWord,cndCr->td_current.zone_id);
  		(*ci0)->stateDWord = cndCr->stateDWord;
  		(*ci0)->td_current.zone_id = cndCr->td_current.zone_id;
  	}
  }

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When running this code, I got the following output:

Code:

---

tasks2 vector size: 2
 
conditions2 vector size: 5
 
stateDWord: 1, zone_id: 2
stateDWord: 3, zone_id: 4
stateDWord: 5, zone_id: 6
stateDWord: 7, zone_id: 8
stateDWord: 9, zone_id: 10
 
conditions2 vector size: 5
 
stateDWord: 1, zone_id: 2
stateDWord: 3, zone_id: 4
stateDWord: 5, zone_id: 6
stateDWord: 7, zone_id: 8
stateDWord: 9, zone_id: 10

---

instead of something like

Code:

---

tasks2 vector size: 2
 
conditions2 vector size: 2
 
stateDWord: 1, zone_id: 2
stateDWord: 3, zone_id: 4
 
conditions2 vector size: 3
 
stateDWord: 5, zone_id: 6
stateDWord: 7, zone_id: 8
stateDWord: 9, zone_id: 10

---

What am I doing wrong? Thank you in advance for the answer.

Already found the answer. I forget to initialize another copy of structure before pushing it to the list.

Code:

---

taskData td2;
  QList<condition_struct*> *conditions2 = new QList<condition_struct*>;
  QList<QList<condition_struct*>* > *tasks2 = new QList<QList<condition_struct*>* >;
 
  condition_struct *cnd2 = new condition_struct;
  cnd2->stateDWord = 1;
  cnd2->td_current.zone_id = 2;
  conditions2->push_back(cnd2);
  cnd2 = new condition_struct;
  cnd2->stateDWord = 3;
  cnd2->td_current.zone_id = 4;
  conditions2->push_back(cnd2);
 
  tasks2->push_back(conditions2);
 
  >>>>> conditions2 = new QList<condition_struct*>;

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I'd recommend not to allocate QLists on the heap in the first place because it's an implicitly shared class. Allocating it on the stack simplifies your code and makes it much less error prone.

jpn

Thank you for your advice, I'll try this.