Thread: I/O operation on binary file

Dear all:

I have the following:

Code:

typedef struct {
        int number;
        char str[15];
} RECORD;

#define NUM_RECORDS (50)

int main () {
        RECORD records;
        int i;
        
        FILE *fptr;

        fptr = fopen ("records.dat", "w+");
        
        for (i=0; i<NUM_RECORDS; i++) {
                records.number = i;
                sprintf(records.str, "RECORD - %d", i);
                fwrite (&records, sizeof(&records), 1, fptr);
        }

        fclose (fp);

        fptr = fopen ("records.dat", "r+");
        fseek (fptr, 30*sizeof(records), SEEK_SET);
        fread (&records, sizeof(records), 1, fptr);

        records.number = 500;
        sprintf(records.str, "RECORD - %d", records.number);

        fseek (fptr, 30*sizeof(records), SEEK_SET);
        fwrite (&records, sizeof(records), 1, fptr);

        fseek (fptr, sizeof(records), SEEK_END);
        rewind (fptr);
        for (i=0; i<NUM_RECORDS; i++) {
                fread(&records, sizeof(records), 1, fptr);
                printf("%d\n", records.number);
                printf("%s\n", records.str);
        }

        fclose (fptr);
        return 0;
}

But it didn't print all 50 records in this format:

0
RECORD - 0
1
RECORD - 1
.
.
.
.

Instead, it prints the following:

0


4

8

12

16

20

24

28

32
!
36
%
40
)
44
-
48
1
0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

500
RECORD - 500
500
RECORD - 500
500
RECORD - 500
500
RECORD - 500
500
RECORD - 500
500
RECORD - 500
500
RECORD - 500

What did I do wrong?

Thanks.

barramundi9

OMG ... I am so dumb ...

Thanks