How does fread() work.

Hello, Ive got an assignment to do, that requires I take a .dat file, with data points sorted like this:

x1 y1 x2 y2 etc.

Unfortunately its arranged for bigendian pcs and one of the assignment takes is to change it to littlendian so the data actually means something,

This is the code I have so far. Basically I know that I have to read in the data, put them into a union as an integer, do bitwise operations on them to rearrange into littleend, and then return that union as a wonderful new float that means something.

I just don't know how fread() works. I've read up on it online, but...its not very clear.
If I have 10 numbers to read, how do i tell it to put them into 10 unions? Is this how it does things normally?

I kind of want teaching more than the answer, if thats k.

Thanks alot.

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>


int status;
FILE *data;
int no_of_floats;
int no_of_datapoints;

typedef struct{
        double x_value;
        double y_value;
}data_point;

typedef union{
        int data_dummy;
}converter;

int main(int argc, char** argv)
{
        struct stat file_status;
        data_point* data_value;
        converter* data_converter;
        int datacheck;
       
        data = fopen("px390_2_bin.dat", "r");
        if (data == NULL) /*Test for error*/
                {
                printf("Error opening file.\n");
                exit(8);
                }
               
        if (stat("px390_2_bin.dat", &file_status) != 0)
        {
        perror("Could not find the size of the file 'px390_2_bin.dat'\n");
        }
        else
        {
        printf("The size of the file is: &#37;ld\n", file_status.st_size);
        }
        no_of_floats = file_status.st_size/sizeof(float);
        printf("The number of data values in the file is: %d\n", no_of_floats);
        no_of_datapoints = no_of_floats / 2;
       
        data_value = (data_point*)malloc(sizeof(data_point) * no_of_datapoints);
       
        data_converter = (converter*)malloc(sizeof(int) * no_of_floats);

        datacheck = fread((char *)&data_converter, sizeof(int), no_of_floats, data);
        if (datacheck != no_of_floats)
    {
            printf ("Error writing data to file.\n");
    }
    else
    {
            printf ("Successfully wrote data to file.\n");
    }
    printf("datacheck = %d\n", datacheck);
    printf("no_of_floats = %d\n", no_of_floats);
    printf("The first int is: %d\n", data_converter[1].data_dummy);
       
        free(data_value);
        return 0;
}

---

I've kinda figured it out through plain desperation.

My fread line should have been this:

Code:

---

datacheck = fread(data_converter, sizeof(int), no_of_floats, data);

---

As in it didn't need a pointer to memory, I think thats because I'd already assigned data_converter its memory using malloc previously, so I guess it just needed to know what array of unions I wanted to put everything into.

Feel free to confirm this though, one of you experienced folk :)