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c++structinitializer

Initialize values of a struct pointer

I am starting to learn binary trees in cpp and dynamically allocated memories; thus to initialize a struct I do this

struct node{
    int val;
    node* left;
    node* right;
};
//Initialize:
node* root = new node;
root->val = 7;
root->left = NULL;
root->right = NULL;

I would like to know if there is a better way to set the struct values without writing the last three lines of code. I saw on some web pages that they do this:

int* n = new int(6);

Thanks!

Solution

  • You can write a custom constructor:

    struct node{
    int val;
    node* left;
    node* right;
    node(int);
};

node::node(int _v){
    this->val = _v;
    this->left = this->right = nullptr;
}

node *root = new node(6); // Works as you want

    Or use member initializer list, which looks simpler:

    struct node{
    int val;
    node* left;
    node* right;
    node(int _v) : val(_v), left(nullptr), right(nullptr) {};
};

    Don't forget the braces after the list.