CODEWITHSUNDEEP
c++memorydynamic-memory-allocationcalloc
Leonardo
Leonardo

Reputation: 1

Equivalent C calloc in C++ for 2d array

I found this code (C code) about a maze generator and i would like to use it in C++ :

{
    int x, y; //Node position - little waste of memory, but it allows faster generation
    void *parent; //Pointer to parent node
    char c; //Character to be displayed
    char dirs; //Directions that still haven't been explored
} Node;

Node *nodes; //Nodes array
int width, height; //Maze dimensions


int init( )
{
    int i, j;
    Node *n;
    
    //Allocate memory for maze
    nodes = calloc( width * height, sizeof( Node ) );
    if ( nodes == NULL ) return 1;
        
    //Setup crucial nodes
    for ( i = 0; i < width; i++ )
    {
        for ( j = 0; j < height; j++ )
        {
            n = nodes + i + j * width;
            if ( i * j % 2 ) 
            {
                n->x = i;
                n->y = j;
                n->dirs = 15; //Assume that all directions can be explored (4 youngest bits set)
                n->c = ' '; 
            }
            else n->c = '#'; //Add walls between nodes
        }
    }
    return 0;
}

the problem comes frome the line nodes = calloc( width * height, sizeof( Node ) ); How can i change it for a C++ code? I would like as possible to avoid to use new as all the code is big.

Upvotes: 0

Views: 219

Answers (1)

tadman
tadman

Reputation: 211680

This is C++ so set calloc aside and use new[]:

Node *n = new Node[width * height];

Even better, std::vector:

std::vector<Node> n(width * height);

Where in both cases it's as easy as:

auto& node = n[i + j * width];

To access individual elements.

You'll also want to make a proper constructor for your Node that sets up those pointers, or at least gives them safe defaults. In that case it might be easier to add them to the vector as you go, like:

 std::vector<Node> n; // Start empty

 // Inside the loops...
 n.emplace_back(i, j, nullptr, ' ', 15);

Upvotes: 1

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