#include <stdio.h>
#include <stdlib.h>

struct vector3d {
   float x;
   float y;
   float z;
};

int main()
{
   FILE *fp;
   struct vector3d myvectors[2];

   fp = fopen("dianismata.txt", "r");
   if (!fp) {
      fprintf(stderr, "Error opening file\n");
      exit(EXIT_FAILURE);
   }

   /* Read vectors' coordinates */
   fscanf(fp, "%f%f%f", 
	  &myvectors[0].x,
	  &myvectors[0].y,
	  &myvectors[0].z);

   fscanf(fp, "%f%f%f",
	  &myvectors[1].x,
	  &myvectors[1].y,
	  &myvectors[1].z);

   /* Print vectors' coordinates */
   printf("v1(x, y, z) = (%f, %f, %f)\n", 
	  myvectors[0].x, 
	  myvectors[0].y, 
	  myvectors[0].z);

   printf("v2(x, y, z) = (%f, %f, %f)\n",
          myvectors[1].x,
          myvectors[1].y,
          myvectors[1].z);

   return EXIT_SUCCESS;
}

------------------------------------------------------------------


[stathis@archlinux Desktop]$ ./a.out 
v1(x, y, z) = (1.000000, 2.000000, 3.000000)
v2(x, y, z) = (-5.000000, -6.500000, 7.000000)