problem with file i/o in binary

[pereges]

I'm having a problem with reading a file that was written in binary.
This is the main structure of the data i want to write:


typedef struct ray_struct
{
double t;
vector origin; /* vector is a struct with 3 doubles x,y , z */
vector d;
int depth;
double efield_x, efield_y;

}ray;

I have two functions, compute_planar_ source() writes the data and
fire_rays() reads the data:

int compute_planar_ source()
{
............... ....

FILE *fp;
fp = fopen("rayinf", "wb");

if(fp == NULL)
{
perror("File could not be opened!");
return FAILURE
}

/* i have left out data structures for minB, maxB and radardetector
but the values are as follows:
minB.y = minB.x = minB.z = -10 a double
maxB.y = maxB.y = maxB.z= 10 a double

xcord and ycord are doubles
radardetector.r ay_spacing is a double and value is 0.05 */

ray *p;

for(ycord = minB.y; ycord<= maxB.y; ycord +=
radardetector.r ay_spacing )
{
for(xcord = minB.x; xcord<=maxB.x; xcord +=
radardetector.r ay_spacing)
{

p = malloc(sizeof(r ay));
if(p == NULL)
{
perror("malloc has failed!");
return FAILURE;
}
p->origin.x = xcord;
p->origin.y = ycord;
p->origin.z = minB.z - 1000;
/* this prints fine : printf("%f %f %f\n", p-

>origin.x, p->origin.y, p->origin.z); */

p->t = DBL_MAX;
p->d.x = 0;
p->d.y = 0;
p->d.z = 1;
p->depth = 0;
p->efield_x = radardetector.E 0;
p->efield_y = 0;
fwrite(p, sizeof(ray), 1, fp);
free(p);
}

}

fclose(fp);

}

int fire_rays()
{
FILE *fp;
ray r;

fp = fopen("rayinf", "rb");

if(fp == NULL)
{
perror("File open failed");
return FAILURE;
}

while(fread(&r, 1, sizeof(ray), fp) == 1)
{
printf("\nOrigi n: %f %f %f\n", r.origin.x, r.origin.y,
r.origin.z); // Doesn't print at all ??
}

}


int main()
{

int i;

i = compute_planar_ source();
if(i == FAILURE)
{
printf("compute _planar_source( ) has failed\n");
}

i = fire_rays();
if(i == FAILURE)
{
printf(" fire_rays() has failed\n");
}

return 0;
}

[pereges]

Re: problem with file i/o in binary


On Apr 28, 2:29 pm, Barry Schwarz <schwa...@dqel. comwrote:

It would be nice if you provided a description of your problem as part
of the discussion and not as a miniscule comment buried in the code

Well the problem was related to ray tracing. I was trying to generate
the rays and store them them on a file. The write operation was
working fine but there was a problem in reading the ray information
from the file.

If you look at your fwrite and your fread statements carefully, the
difference in the way you coded them should give you enough of a hint
to solve the problem. Otherwise, read my comment at the fread
statement.

Thanks for your help. I realize the problem was in fread().