How to dynamically allocate memory to a array of array in C?

Question

I have the following C struct :

typedef struct {

    char *name;
    int nfollowers;
    char *followers[];
} User;

There's a point in my code where I have to allocate memory for the last variable of the struct ( followers ) and I'm having issues on it.

I have tried this:

users[nusers].followers = (char **) realloc(users[nusers].followers, sizeof(char));

or this

users[nusers].followers = (char **) realloc(users[nusers].followers, sizeof(char *));

but the output I get after compiling is the following:

error: invalid use of flexible array member

How can I properly do this?

EDIT

Example of how my C file is structured:

 User *users;
 int i=0, n, nusers=0;
 char aux, *str;
 
 fd_in = open(argv[1], O_RDONLY);
 
 if (fd_in >= 0) {

    users = (User *) malloc(sizeof(User));

    while (aux!='&') {

        users[nusers].followers = (char **) realloc(users[nusers].followers, sizeof(char)); //Issue

          while (aux != '#') {
              ...
          }
      }
  }

Answer 1

As mentioned by tadman, instead of char *followers[]; use char **followers; to declare the field.

Also watch out that malloc does not initialize memory (though on linux the memory might be initialized to 0 if it has not been reused) so your use of realloc may result in corrupting the heap. Instead, just use malloc again (or use calloc to allocate the struct).