How can I create objects while adding them into a vector

Question

I have a C   vector  I want the vector to hold a variable number of objects    Visual Studio 2012 is giving me an error     Error  type name is not allowed   From this C   code    include  lt iostream gt   include  lt vector gt  using namespace std   class testObject  private     int someInt  public     testObject int a   someInt a       void show     cout lt  lt someInt lt  lt endl        int main         vector lt testObject gt  testVector      cout  lt  lt   Initial size     lt  lt  testVector size    lt  lt endl       for   int i   0  i  lt  3  i             testVector push back testObject 3        cout  lt  lt   New size     lt  lt  testVector size    lt  lt  endl       for   int j   0  j  lt  3  j             testVector  j   show         system  pause            But here s another sample of code that looks the same but it s not working   void Dealer  setNumberOfPlayers  const int tNumber         for   int i   0  i  lt  tNumber  i             vectorOfGamers push back Player      Player is a class that I created     Can I create vector to hold objects of Dealer  Bot and Player at the same time  How do I do that  As I know  all objects in vector should be of one type

User · Answer

I know the thread is already all  but as I was checking through I ve come up with a solution  code listed below   Hope it can help   include  lt iostream gt   include  lt vector gt   class Box       public       static int BoxesTotal      static int BoxesEver      int Id       Box                   BoxesTotal            BoxesEver          Id   BoxesEver          std  cout  lt  lt   quot Box   quot   lt  lt  Id  lt  lt   quot   quot   lt  lt  BoxesTotal  lt  lt   quot   quot   lt  lt  BoxesEver  lt  lt   quot   initialized  quot   lt  lt  std  endl              Box                 std  cout  lt  lt   quot Box   quot   lt  lt  Id  lt  lt   quot   quot   lt  lt  BoxesTotal  lt  lt   quot   quot   lt  lt  BoxesEver  lt  lt   quot   ended  quot   lt  lt  std  endl          --BoxesTotal             int Box  BoxesTotal   0  int Box  BoxesEver   0   int main int argc  char  argv          std  cout  lt  lt   quot Objects  Boxes  example  quot   lt  lt  std  endl      std  cout  lt  lt   quot ------------------------ quot   lt  lt  std  endl       std  vector  lt Box  gt  BoxesTab       Box  Indicator      for  int i   1  i lt 4    i                std  cout  lt  lt   quot i    quot   lt  lt  i  lt  lt   quot   quot   lt  lt  std  endl          Box  Indicator   new Box           BoxesTab push back Indicator           std  cout  lt  lt   quot Adres Blowera   quot   lt  lt   BoxesTab i-1   lt  lt  std  endl             std  cout  lt  lt   quot Summary quot   lt  lt  std  endl      std  cout  lt  lt   quot ------- quot   lt  lt  std  endl      for  int i 0  i lt 3    i                std  cout  lt  lt   quot Adres Blowera   quot   lt  lt   BoxesTab i   lt  lt  std  endl             std  cout  lt  lt   quot Deleting quot   lt  lt  std  endl      std  cout  lt  lt   quot -------- quot   lt  lt  std  endl      for  int i 0  i lt 3    i                std  cout  lt  lt   quot Deleting Box   quot   lt  lt  i 1  lt  lt   quot    quot   lt  lt   BoxesTab i   lt  lt   quot    quot   lt  lt  std  endl          Indicator    BoxesTab i            delete Indicator              return 0     And the result it produces is  Objects  Boxes  example  ------------------------ i   1  Box  1 1 1  initialized  Adres Blowera  0xdf8ca0 i   2  Box  2 2 2  initialized  Adres Blowera  0xdf8ce0 i   3  Box  3 3 3  initialized  Adres Blowera  0xdf8cc0 Summary ------- Adres Blowera  0xdf8ca0 Adres Blowera  0xdf8ce0 Adres Blowera  0xdf8cc0 Deleting -------- Deleting Box  1  0xdf8ca0   Box  1 3 3  ended  Deleting Box  2  0xdf8ce0   Box  2 2 3  ended  Deleting Box  3  0xdf8cc0   Box  3 1 3  ended

User · Answer

Question 1      vectorOfGamers push back Player    This is problematic because you cannot directly push a class name into a vector  You can either push an object of class into the vector or push reference or pointer to class type into the vector  For example   vectorOfGamers push back Player name  id          assuming name and id are parameters to the vector  call Player constructor       In other words  push  instance   of Player class into vector   Question 2   These 3 classes derives from Gamer  Can I create vector to hold objects of Dealer  Bot and Player at the same time  How do I do that   Yes you can  You can create a vector of pointers that points to the base class Gamer  A good choice is to use a vector of smart pointer  therefore  you do not need to manage pointer memory by yourself  Since the other three classes are derived from Gamer  based on polymorphism  you can assign derived class objects to base class pointers  You may find more information from this post  std  vector of objects   pointers   smart pointers to pass objects  buss error  10

User · Answer

create a vector of unknown players  std  vector lt player gt  players      resize said vector to only contain 6 players  players resize 6     Values are always initialized  so a vector of 6 players is a vector of 6 valid player objects   As for the second part  you need to use pointers  Instantiating c   interface as a child class

User · Answer

You cannot insert a class into a vector  you can insert an object  provided that it is of the proper type or convertible  of a class though   If the type Player has a default constructor  you can create a temporary object by doing Player    and that should work for your case   vectorOfGamers push back Player

User · Answer

To answer the first part of your question  you must create an object of type Player before you can use it  When you say push back Player   it means  add the Player class to the vector   not  add an object of type Player to the vector   which is what you meant    You can create the object on the stack like this   Player player  vectorOfGamers push back player          lt -- name of variable  not type   Or you can even create a temporary object inline and push that  it gets copied when it s put in the vector    vectorOfGamers push back Player            lt -- parentheses create a  temporary    To answer the second part  you can create a vector of the base type  which will allow you to push back objects of any subtype  however  this won t work as expected   vector lt Gamer gt  gamers  gamers push back Dealer           Doesn t work properly    since when the dealer object is put into the vector  it gets copied as a Gamer object -- this means only the Gamer part is copied effectively  slicing  the object  You can use pointers  however  since then only the pointer would get copied  and the object is never sliced   vector lt Gamer  gt  gamers  gamers push back new Dealer            lt -- Allocate on heap with  new   since we                                       want the object to persist while it s                                       pointed to

[c++] How can I create objects while adding them into a vector?

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