read %s %s %d %d to struct from records.dat using fscanf

Hello folks,
what i'm trying to do is to read data separated by whitespaces (' ', '\t') from file using fscanf
and put it into struct array
here's a piece of code:

Code:

typedef struct
{
  char id[4], name[20];
  int grade;
}rec;
...
rec recs [10]
...
while(fscanf(f, "%[^ ]%[^ ]%d", recs[i].id, recs[i].name, &recs[i],grade)) 
{
   printf("%s %s %d", recs[i].id, recs[i].name, recs[i].grade);
   i++;
}

it doesn't print it as it should.
i know that the problem is in reading (in second arg of fscanf)...

any ideas?

So what is the input, and what is the output? Also you messed up with "&reces[i],grade".


Quzah.

ok, when I do

Code:

       ....
       i=0;
	while ( fscanf ( f, "%[^ ]%[^ ]%d", recs[i].id, recs[i].name,	&recs[i].grade )!=EOF) 

	{

		printf("%s %s %d\n", recs[i].id, recs[i].name, recs[i].grade);

		i++;

	}

it prints so much garbage.... it like takes couple of seconds to print that garbage.
And then it ends with segmentation fault on the line where while bracket closes...
What could be the problem?

Perhaps the input is too large to fit into the arrays.

Originally Posted by laserlight

Perhaps the input is too large to fit into the arrays.

record.dat
ABC John 3
DEF Jack 4

not that large

Well... to be on the safe side, I suggest that you define a function like this:

Code:

int readRec(FILE *fp, rec *record)
{
    return fscanf(fp, "%3s %19s %d", record->id, record->name, &record->grade) == 3;
}

then you change the loop to:

Code:

for (i = 0; i < 10 && readRec(f, &recs[i]); ++i)
{
    printf("%s %s %d\n", recs[i].id, recs[i].name, recs[i].grade);
}

hey thanx laserlight, it worked
but i get
ABCJohn John 3
DEFJack Jack 4

Sorry, I cannot duplicate that using what I suggested.

its strange, because when im printing only id's
it prints
ABCJohn
DEFJack

That implies that id is storing a string of length greater than 3 (i.e., buffer overflow), but that is impossible because I put in that length of 3 restriction in the format specifier to specifically prevent that.

yeah thats the thing, man
also in struct it is already defined as char id[3]

Originally Posted by r00t

also in struct it is already defined as char id[3]

You correctly declared it as char id[4], actually. Unfortunately, that is of no help since it is possible to write beyond the array bounds, resulting in undefined behaviour.

I suggest that you post the smallest and simplest compilable program that demonstrates the problem. Check that your input is correct as well.

Code:

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

{

	char id[4], name[20];

	int grade;

}rec;
int readRec(FILE *fp, rec *record);

int main(void)

{
    FILE *f;

    int i;

	

    rec recs[10];



    f = fopen ("record.dat", "r" );

    if ( f == NULL )

    {

	printf("Cannot open record file");

	exit(1);

    }

    for (i = 0; i < 10 && readRec(f, &recs[i]); ++i)
    {
    	printf("%s %s %d\n", recs[i].id, recs[i].name, recs[i].grade);
    }

    return 0;
}
int readRec(FILE *fp, rec *record)
{
    return fscanf(fp, "%3s %19s %d", record->id, record->name, &record->grade) == 3;
}

heres the working program
hey you know what, my id was of length 3.... omg... i put 4, and its working.. my bad
thanx a lot, laserlight

Originally Posted by r00t

hey you know what, my id was of length 3.... omg... i put 4, and its working.. my bad

Ah, so we could explain your earlier problem as: the name was overwriting the null terminator for the id, thus the id and name were printed as if they were concatenated when you only print the id.