Allocate memory for a vector of pointers inside of a structure

Question

I have the following structure:

struct node{
  char name;
  vector<node*> children;

  void addChild(char name){
    node *newChild = (node*)malloc(sizeof(node));
    newChild->name = name;
    children.push_back(newChild);
  }
};

The code above compiles but crashes with a std::bad_alloc prompt whenever addChild is called for any node that was created using addChild.

It seems to me like i should somehow be allocating memory for the vector as well, but i am unsure about how i would go about doing that.

I am a "begginer" and know very little about memory allocation so any help would be appreciated.

Thanks in advance.

score 6 · Accepted Answer · answered Jun 26 '17 at 01:48

6

Don't use malloc and free in C++. Especially for objects that needs to have their constructor called, since malloc does not call the constructor.

In your case it means that the std::vector constructor will not be called, and you will have undefined behavior when you use the vector.

Use new and delete instead.

Any good beginners book should have told you this.

answered Jun 26 '17 at 01:48

Some programmer dude

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yup. replacing `node *newChild = (node*)malloc(sizeof(node));` with `node *newChild = new node` made it work. Thank you! – Sebastián Mestre Jun 26 '17 at 01:59

Allocate memory for a vector of pointers inside of a structure

1 Answers1