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Jan 29th, 2010
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how to track objects and put them on a vector ?

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hello can I keep track of objects in a list and being able to sort them by there z var ?

do I use pointers ?
how would I do this ?

C++ Syntax (Toggle Plain Text)
  1. #include <vector>
  2.  
  3. vector<sometype> _objects_;
  4.  
  5. create_object(object_type)
  6. {
  7.     new object_type myobject;
  8.     _objects_.push_back(myobject);
  9.     return _objects_.at(list_end);
  10. }
  11.  
  12. remove_object(int pos)
  13. {
  14.     delete *_objects_.at(pos);
  15.     _objects_.erase(pos);
  16.  
  17. }
  18.  
  19. sort_object_list()
  20. {
  21.     object_list.sort(object.z);
  22. }
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wwsoft is offline Offline
29 posts
since Jan 2010
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Jan 29th, 2010
1
Re: how to track objects and put them on a vector ?
You can supply a predicate to the sort template from <algorithm> that does the comparison:
C++ Syntax (Toggle Plain Text)
  1. #include <algorithm>
  2. #include <vector>
  3.  
  4. void sort_object_list ( std::vector<sometype>& object_list )
  5. {
  6.   struct compare {
  7.     bool operator() ( const sometype& a, const sometype& b )
  8.     {
  9.       return a.z < b.z;
  10.     }
  11.   };
  12.  
  13.   std::sort ( object_list.begin(), object_list.end(), compare() );
  14. }
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Narue is offline Offline
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Jan 29th, 2010
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Re: how to track objects and put them on a vector ?
so how can I make this accept all object types ?
C++ Syntax (Toggle Plain Text)
  1. create_object(object_type)
  2. {
  3.     new object_type myobject;
  4.     _objects_.push_back(myobject);
  5.     return _objects_.at(_objects_.end);
  6. }
Last edited by wwsoft; Jan 29th, 2010 at 6:16 pm.
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wwsoft is offline Offline
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Jan 29th, 2010
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Re: how to track objects and put them on a vector ?
Click to Expand / Collapse  Quote originally posted by wwsoft ...
so how can I make this accept all object types ?
C++ Syntax (Toggle Plain Text)
  1. create_object(object_type)
  2. {
  3.     new object_type myobject;
  4.     _objects_.push_back(myobject);
  5.     return _objects_.at(_objects_.end);
  6. }
As long as your vector will contain homogenous types (i.e. they are all the same). You could use a templated function:

C++ Syntax (Toggle Plain Text)
  1. template<class T>
  2. T& create_object( vector<T> objects ){
  3.    T obj;
  4.    objects.push_back( obj );
  5.    return objects.back();
  6. }

Please note that there is no good method for creating a container class to hold heterogenous data in c++. If you were brave, you could create a vector of void pointers, but you would have no way of knowing the type each element.

If you all of the items you need to put in the container are user defined types, then you could have each class inherit from some arbitrary base class, and then you could create a vector of pointers to the base type object:
C++ Syntax (Toggle Plain Text)
  1. class Derived1 :  public Base{....}
  2. class Derived2 : public Base{...}
  3. vector<Base*> v;
  4. Derived1 a;
  5. Derived2 b;
  6. v.push_back(&a);
  7. v.push_back(&b);
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dusktreader is offline Offline
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since Jan 2010
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Jan 30th, 2010
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Re: how to track objects and put them on a vector ?
Thanks for the help !
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wwsoft is offline Offline
29 posts
since Jan 2010

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