C struct into array of struct pointers compile error

Question

I've got a linked list and I'm trying to make a temporary array to help me address each node while I build the rest of the structure, then I intend to free the array but it seems I can't store the address of the struct into a pointer array.

Here's a boiled down version of where I'm having problems:

vertex *vertexIndex = NULL;
vertex *vertexHead = NULL;
vertexHead = malloc(sizeof(vertex));
vertexHead->vertexNum = 5;
vertexIndex = malloc(sizeof(vertex*));
vertexIndex[0] = vertexHead;            //<<<<<<<<<<<  Error on this line
printf("%u\n", (vertexHead[0])->vertexNum);

main.c:72:19: error: incompatible types when assigning to type 'vertex' from type 'struct vertex *'

Any help would be greatly appreciated.

EDIT

Here are the structs

struct edgeStruct {
    unsigned int edgeTo;
struct edgeStruct *nextEdge;
};
typedef struct edgeStruct edge;

struct vertexStruct {
    unsigned int vertexNum;
    edge *edgeHead; 
    struct vertexStruct *nextVertex;
};
typedef struct vertexStruct vertex;

Answer 1

vertexIndex应该是指向指针的指针，因为您将它用作指针数组。

vertex **vertexIndex = NULL;

Answer 2

vertexIndex is not an array of struct. It's just a struct pointer which is why you are getting the error.

If you want an array, declare an array: vertex

vertex *vertexHead[10]; //array of 10 pointers

Now, you'll be able to use it as you do now.

Answer 3

As the error message says, on that line you are trying to assign content of pointer to the pointer ie. assigning vertexHead which is vertex * to *vertexIndex (equivalent to vertexIndex[0] which are not compatible.

It will be better you post your code of definition of vertex so that people can suggest what should be done preferably.