Freeing structs correctly

Question

I'm trying to free a struct and am having trouble with it. What I'm programming is kind of an n-ary tree or a virtual file system. I have 2 different structs (one for folders and one for files) and an array for each struct where every element is stored. The structs have a member ID and I've made so I can get a file/folder by using Folders[ID], which will return the struct with that ID. The problem I have is deleting / freeing them. First of all, if it is a folder that will be deleted, it will check recursively for children files and folders and delete these first. For some reason, I just can't get the free() to work, no matter what I try.

My Folder struct:

typedef struct {
    FolderID selfID;
    FolderID parentID;

    /* Other members are not important */
} FolderInfo;

My array:

FolderInfo Folders[MAX_FOLDERS];

How the FolderInfo structs are added to the array (In my new_folder function):

/* ... */
FolderInfo *this = malloc(sizeof (FolderInfo));
/* ... */
ID++;
Folders[ID] = *this;
/* ... */

The delete function:

int32_t delete_folder(FolderID ID) {
    if(FolderIsEmpty(ID) == 1) {
        return -1; /* Error */
    }

    /* Check for children and delete them recursively */

    /* ... */

    free(Folders[ID]);
    return 0;
}

Everytime I create a new file/folder, it is added to the file/folder array under the index ID , so Folders[ID] should get the struct with that ID. What am I missing here?

Thanks in advance

Answer 1

Change

FolderInfo Folders[MAX_FOLDERS] 

to

 FolderInfo* Folders[MAX_FOLDERS] 

and

Folders[ID] = *this 

to

 Folders[ID] = this. 

Of course, you can simply refrain from using malloc and free to begin with.