Question

I am creating a simple graph with nodes and edges. I got the functionality going but got some memory bugs.

I have a typedef struct in header file:

typedef struct Graph_s* Graph;

And implementation in c. file:

struct Graph_s {
    Node* nodeArray;
    Edge* edgeArray;  
    size_t edges;
    size_t nodes;
};

And function for construction:

Graph create_graph() {
    Graph newGraph = malloc(sizeof(Graph)); 

    newGraph->edges = 0;
    newGraph->nodes = 0;
    return newGraph;
}

The line Graph newGraph = malloc(sizeof(Graph)) gives: Invalid write of size 8 from Valgrind.

Answer 1

malloc(sizeof(Graph)) is only allocating enough memory for a pointer. Change it to malloc(sizeof(struct Graph_s)).