动态地分配对象数组 [英] Dynamically allocating array of objects

问题描述

我需要的类型DizzyCreature（我班）的双指针指向DizzyCreature指针数组。当我运行它，我得到访问冲突读取位置0X ......。我可以做一个DizzyCreature *并调用它的成员函数就好了，但是，当无法通过阵列运行，并做同样的事情对每个OBJ。

I need a double pointer of type DizzyCreature (my class) to point to an array of DizzyCreature pointers. When I run it I get "Access violation reading location 0x...". I can make a DizzyCreature* and call its member functions just fine, but when cannot run through the array and do the same thing for each obj.

我以下说明：
http://www.cplusplus.com/forum/beginner/10377/

code

Server.h：

class Server
{
 public:
  Server(int x, int y, int count);
  ~Server(void);

  void tick();


 private:
  DizzyCreature** dcArrPtr;
  DizzyCreature* dcPtr;

  int _count;
};

Server.cpp：

Server.cpp:

Server::Server(int x, int y, int count)
{
  dcPtr = new DizzyCreature[count];       // this works just fine

  dcArrPtr = new DizzyCreature*[count];   // this doesn't (but gets past this line)
  _count = count;
}

Server::~Server(void)
{
  delete[] *dcArrPtr;
  delete[] dcPtr;
}

void Server::tick()
{
  dcPtr->takeTurn();                // just fine

  for (int i = 0; i < _count; i++) {
    dcArrPtr[i]->takeTurn();        // crash and burn
  }
}

编辑：
成员函数takeTurn（）是在父类DizzyCreature的。该方案使得它进入的功能，但只要它试图改变一个私有成员变量中的异常。如果它的事项，DizzyCreature的类型是GameCreature和WhirlyB的，因为这是对MI赋值。

The member function takeTurn() is in a parent class of DizzyCreature. The program makes it into the function, but as soon as it attempts to change a private member variable the exception is thrown. If it matters, DizzyCreature is of type GameCreature and WhirlyB as this is an assignment on MI.

推荐答案

您已经分配的空间，但此数组中没有分配每个对象。您必须执行以下操作：

You have allocated space for dcArrPtr, but didn't allocate every object in this array. You must do following:

Server::Server(int x, int y, int count)
{
  dcPtr = new DizzyCreature[count];

  dcArrPtr = new DizzyCreature*[count];
  for ( int i = 0; i < count; i++ ) {
    dcArrPtr[ i ] = new DizzyCreature;
  }
  _count = count;
}

Server::~Server(void)
{
  for ( int i = 0; i < count; i++ ) {
    delete dcArrPtr[ i ];
  }
  delete[] *dcArrPtr;
  delete[] dcPtr;
}

这篇关于动态地分配对象数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！