reading structures from a file

I want to be able to create a structure record (person name, id number, rating) and save it to a file. I then want to be able to pull the person based on ID number. How? I have tried using the fwrite and fread commands, but I can only "write" one structure at a time. And upon reading it back, I can't seem to pull individual data based on a certain criteria. I'm new at programming, what is it I'm missing about writing and reading info to files??

fread/fwrite(void * data, unsigned packets, size_t size_of_packet, FILE * file)

So ten structs at once would be :

struct Struct array[10];
int size = sizeof(Struct);

int success == fread(array, 10, size, file);

or even:

success == fread(array, 1, size * 10, file);

or even:

success == fread(array, size * 10, 1, file);

or:

while(size == fread(array, 1, size, file))
continue;

So pretty flexible to use these functions. Just read the return value and if is not the same number you passed as the second parameter to fread/fwrite, then an error occured such as end of file, unopened or invalid FILE handles, etc...

>>So pretty flexible to use these functions
Unless the structure uses pointers to anonymous memory, such as a name. If this is the case then onlny the value of the pointer will be saved, not the memory it points to. So if your structure looks like this

Code:

---

typedef struct {
  char *name;
  long id_num;
  long rating;
} PERSON;

---

Then using fread won't work to write any one of the structures to file. You'd have to write each member of each structure manually and read them back manually :-)

Like hard-coded buffers of known size.

unsigned id;
char name_buffer[128];
char address_buffer[128];