Question

I’m trying to understand why the assignment g.node = n1; isn’t possible.

Can anyone explain?
The idea is to create a graph with nodes using structures. I thought this method would work, but I get error: incompatible types in assignment for g.node = n1;

#include <stdio.h>

typedef struct
{
    int value;
    int *edges;
    int *adj;
}  Node;

typedef struct
{
    Node *node;

} Graph;

void resize_array(char *, int);
void copy_array  (char *, char *);
int main()
{
    Graph g;
    Node n1, n2;
    int edgesS[1] = {9};
    int adjS[1] = {5};
    n1.edges = edgesS;
    n1.adj = adjS;
    n1.value = 1;
    g.node = n1;
    return 0;
}

void resize_array(char * array, int size){array[size] = '\0';}

Answer 1

g.node is of type Node* but n1 is of type Node. The assignment would be possible as

g.node = &n1;

instead. Note that g.node merely points to a Node; it doesn’t contain the memory for one. With the above simple assignment, when n1 goes out of scope, the memory g.node points to becomes invalid.