Thread: binary file work using structs and enum

Hello everyone,
I get a "Segmentation Fault" when I try to run this program. I think my problem is with the structs and enum. Specifially the enum but I could be wrong. I have enclosed my classes.h file and loadFile.c file.

Code:

#ifndef CLASSES_H_INCLUDED
#define CLASSES_H_INCLUDED

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

typedef enum {MW, TR} days;

typedef struct {
    int hour, min;
} Time;

typedef struct {
    char Dept[5];
    int course, sect;
    days meet_days;
    Time start, end;
    char instr[20];
} sched_record;


#endif // CLASSES_H_INCLUDED

Code:

#include "classes.h"

void main()
{
    FILE *filePointer;
    sched_record data;

    filePointer = fopen ("classes.db", "rb");
    if (filePointer == NULL)
    {
        puts("Cant open file");
        exit(1);
    }
    while (!feof(filePointer))
    {
        if(fread(&data, sizeof(sched_record), 1, filePointer)!=0)
        {
            printf("\n%s %d %d %s %d %d %s", data.Dept, data.course, data.sect, data.meet_days, data.start, data.end, data.instr);
            fclose(filePointer);
        }
    }
}

The file we are to use is a binary file and it is called classes.db. Now we have a text representation and it is as follows:

Code:

Math 102 10 M 0800 0850 Schulte
Eng  033  1 T 0930 1050 Shakespeare
Art  308  2 M 0800 1150 VanGogh
Anth 055 13 T 1200 1325 Kroeber
CS   125  2 T 0800 0850 Hoare
Eng  202 10 M 1000 1050 Chaucer
Chem 100  5 T 1100 1250 Pauling
Phys 395  2 T 1200 1250 Einstein
CS   125  4 M 1030 1120 Knuth
Math 420  2 T 0800 0950 al-Khowarizmi

Does anyone know how I might correct this? I appreciate any help.

Here's what I get when I compile your code:

Code:

$ make sched
gcc -Wall -g -std=c99  -lm -lpthread -lcurses -lefence  sched.c   -o sched
sched.c:18: warning: return type of ‘main’ is not ‘int’
sched.c: In function ‘main’:
sched.c:33: warning: format ‘%s’ expects type ‘char *’, but argument 5 has type ‘unsigned int’
sched.c:33: warning: format ‘%d’ expects type ‘int’, but argument 6 has type ‘Time’
sched.c:33: warning: format ‘%d’ expects type ‘int’, but argument 7 has type ‘Time’

• It's int main(void) and return an int at the end, usually 0. Read this: FAQ > main() / void main() / int main() / int main(void) / int main(int argc, char *argv[]) - Cprogramming.com.
• %s is for printing strings. data.meet_days is an enum (a type of int). You need an if statement (or conditional/ternary) to turn that enum value into a string. This may involve breaking that printf statement into 2 or 3 separate ones.
• %d is for ints, but data.start is a struct. You need data.start.hour, etc.
• Don't close the file after you read one line. Move the fclose after your loop.
• Also, don't use feof to control your loop. Read this: FAQ > Why it's bad to use feof() to control a loop - Cprogramming.com.

That should help a bit.

Thank you very much! Just need to change the enum. Looking that up now.

Ok, got it working.

Code:

#ifndef CLASSES_H_INCLUDED
#define CLASSES_H_INCLUDED

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

#define BINFILE "classes.bin"

typedef enum {MW, TR} days;

typedef struct {
    int hour, min;
} Time;

typedef struct {
    char Dept[5];
    int course, sect;
    days meet_days;
    Time start, end;
    char instr[20];
} sched_record;


#endif // CLASSES_H_INCLUDED

Code:

#include "classes.h"

int main(void)
{
    FILE *filePointer;
    sched_record data;

    filePointer = fopen (BINFILE, "rb");
    if (filePointer == NULL)
    {
        puts("Cant open file");
        exit(1);
    }
    while (!feof(filePointer))
    {
        if(fread(&data, sizeof(sched_record), 1, filePointer)!=0)
        {
            printf("\n%s %d %d %2s %02d%02d ", data.Dept, data.course, data.sect, data.meet_days== MW ? "MW" : "TR", data.start.hour, data.start.min);
            printf("%02d%02d %s", data.end.hour, data.end.min, data.instr);
        }
    }

    fclose(filePointer);

    return 0;
}