Thread: saving/retriving strctures from files

i have an array of a a structure, called videos and i want to save it to file and then load it back in to memory later, so far i have the following code:

//to open the file, fname being the file name, and opp being the mode either rb or wb

tfile = fopen(fname, opp);

//to write the structure to the file
fwrite(&video, 8800, 1, tfile);
fclose(tfile);

this bit works i have looed in the file and it apers to contain the correct information, however the read bit dosent work, the code is the same except for this:

fwrite(&video, 8800, 1, tfile);

anyone know how to get this to work??

You should not put a hardcode number in the function call-- you should always use the 'sizeof' statement.

prototype:
----------
fwrite(void *buffer,size_t elem_size,int num_elem,FILE *stream);

buffer = your buffer filled with data-- this can be a single struct, or a single-dim'd array of struct of like-size.

elem_size = size of individual structure. If you are writing an array of structs, this could simply be the size of the entire array.

num_elem = number of individual structures/elements. If you were writing an entire array, then this could just be a one, so long as 'elem_size' is as big as all the structures in the array.

stream = record for the file control block.

---

So, instead of using fwrite the way you do, rewrite it like so:

Code:

typedef struct
   {
   int   yearMade;         /* when video made (c) */
   char actors[5][35];     /* actor names */
   long   runTime;         /* running time, minutes */
   char   rating[6];       /* movie rating */
   }videoStruc;

int main(void)
   {
   videoStruc video;       /* declare vars */
   FILE tfile = 0L;

   ...

   fwrite(&video,sizeof(videoStruc),1,tfile);
   ...
   return(0);
   }

fopen() is very nearly the same, just moving data in a different direction. In both cases, you should position the file pointer prior to reading/writing so that it is where you expect it. You should also be checking for errors.

enjoy.

i tried:

fwrite(&video, sizeof(video), 1, tfile);
and
fwrite(&video, sizeof(video), 1, tfile);

and it still does not read the file but it does write them.

never mind got it working