创建一个对象指针数组C ++ [英] creating an array of object pointers C++

问题描述

我想创建一个数组来保存指向很多对象的指针，但我不知道预先保存的对象数量，这意味着我需要为数组动态分配内存。我想到了下面的代码：

  ants = new * Ant [num_ants]; 
 for（i = 1; i  {
 ants [i-1] = new Ant 
} 
  

其中 ants 定义为 Ant ** ants; 和 Ant 是一个类。

$ b

解决方案

它会工作吗？

是的。

但是，如果可能，您应该使用向量：

  #include< vector> 
 
 std :: vector< Ant *>蚂蚁
 for（int i = 0; i  ants.push_back（new Ant（））; 
} 
  

如果你必须使用动态分配的数组，

  typedef Ant * AntPtr; 
 AntPtr * ants = new AntPtr [num_ants]; 
 for（int i = 0; i  ants [i] = new Ant（）; 
} 
  

但忘记了。代码仍然没有任何好处，因为它需要手动内存管理。要解决此问题，您可以将代码更改为：

  std :: vector< std :: unique_ptr< Ant>蚂蚁
 for（auto i = 0; i！= num_ants; ++ i）{
 ants.push_back（std :: make_unique< Ant>（））; 
} 
  

最好的一点是：

  std :: vector< Ant>蚂蚁（num_ants）; 
  

I want to create an array that holds pointers to many object, but I don't know in advance the number of objects I'll hold, which means that I need to dynamically allocate memory for the array. I have thought of the next code:

ants = new *Ant[num_ants];
for (i=1;i<num_ants+1;i++)
{
    ants[i-1] = new Ant();
}

where ants is defined as Ant **ants; and Ant is a class.

Will it work?

解决方案

Will it work?

Yes.

However, if possible, you should use a vector:

#include <vector>

std::vector<Ant*> ants;
for (int i = 0; i < num_ants; ++i) {
    ants.push_back(new Ant());
}

If you have to use a dynamically allocated array then I would prefer this syntax:

typedef Ant* AntPtr;
AntPtr * ants = new AntPtr[num_ants];
for (int i = 0; i < num_ants; ++i) {
    ants[i] = new Ant();
}

But forget all that. The code still isn't any good since it requires manual memory management. To fix that you could to change your code to:

std::vector<std::unique_ptr<Ant>> ants;
for (auto i = 0; i != num_ants; ++i) {
    ants.push_back(std::make_unique<Ant>());
}

And best of all would be simply this:

std::vector<Ant> ants(num_ants);

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