c - How can I save a structure which contains allocated memory to file? -

// headers  struct address{   int id;   char *name;   char *email; };  struct database{   struct address *rows;   int max_size;   int max_data; };  struct connection{   file *file;   struct database *db;  };  int main(int argc, char *argv[]){   int i;   struct connection *conn;    conn->file = fopen(argv[3], "w+");   conn->db->max_size = atoi(argv[1]);   conn->db->max_data = atoi(argv[2]);    conn->db->rows = malloc(sizeof(struct address) * (db->max_size));    for(i=0; i<db->max_size; i++){     struct address adr = {.id = i};     adr.name = malloc(conn->db->max_data);     adr.email = malloc(conn->db->max_data);      conn->db->rows[i] = addr;   }    /* other code(s) here    *    *   */ } 

now, according these snipped code, how can save conn->db structure conn->file contents? after that, must able read file, again.

i can't use stack type structure, because "max_data" , "max_size" typed user!

have looked writing binary file.

for writing

file *write_ptr;  write_ptr = fopen("test.bin","wb");  // w write, b binary fwrite(conn->db,sizeof(conn->db),1,write_ptr); // write number of bytes determined structure size binary file 

for reading file

file *read_ptr;  read_ptr = fopen("test.bin","rb");  // r read, b binary fread(conn->db,sizeof(conn-db),1,ptr); // read bytes determined size of structure form file current conn->db structure  

note binary files cant opened , read in paintext

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