Visual Studio 2019 getting error C2440 with typedef data type

Question

I'm getting that problem and don't know how to solve it:

That error:

error C2440: '=': cannot convert from 'void *' to 'node_t'

Code is:

node_t* arr = malloc(sizeof(node_t) * temp3);
    for (int i = 0; i < temp3; i++)
        arr[i] = NULL;

Thanks.

Answer 1

The type of arr[i] is node_t which is not a pointer type (I guessed this from the error message).

This code reproduces the problem:

#include <stdio.h>
#include <stdlib.h>

typedef struct
{
  int a, b;
} node_t;


int main() {
  node_t* arr = malloc(sizeof(node_t) * 10);
  for (int i = 0; i < 10; i++)
    arr[i] = NULL;    
}

You probably need something like this:

void initialize_node(node_t *node)
{
  // adapt this to your actual node_t type
  node->a = 0;
  node->b = 0;
}

int main() {
  node_t* arr = malloc(sizeof(node_t) * 10);
  for (int i = 0; i < 10; i++)
    initialize_node(&arr[i]);
}