Question

so I am trying to read a filesystem disk, which has been provided.

So, what I want to do is read the 1044 byte from the filesystem. What I am currently doing is the following:

if (fp  = fopen("filesysFile-full", "r")) {
  fseek(fp, 1044, SEEK_SET);        //Goes to 1024th byte
  int check[sizeof(char)*4];        //creates a buffer array 4 bytes long
  fread(check, 1, 4, fp);           //reads 4 bytes from the file
  printf("%d",check);               //prints 
  int close = fclose(fp);
  if (close == 0) {
    printf("Closed");
  }
}

The value that check should be printing is 1. However I am getting negative values which keep changing everytime I run the file. I don’t understand what I am doing wrong. Am I taking the right approach to reading bytes of the disk, and printing them.

What I basically want to do is read bytes of the disk, and read the values at certain bytes. Those bytes are fields which will help me understand the structure/format of the disk.

Any help would be appreciated.
Thank you.

Answer 1

This line:

int check[sizeof(char)*4];

allocates an array of 4 ints.

The type of check is therefore int*, so this line:

printf("%d",check);

prints the address of the array.

What you should do it allocate it as an int:

int check;

and then fread into it:

fread(&check, 1, sizeof(int), fp);

(This code, incidentally, assumes that int is 4 bytes.)