Thread: Ansi C - check file size in bytes.

Sure, open the file ("rb"), go to the end with fseek() and find out where you are with ftell().

This is how you do it using standard libraries. st_size sounds like the stat() function in Unix/Linux.

Code:

long size;
FILE *f = fopen("filename", "rb");
if (f)
{
   fseek(f, 0 SEEK_END);
   size = ftell(f);
   fclose(f);
}

--
Mats

i assume you forgot a "," between o and seek: fseek(f, 0 SEEK_END);

i've tried that method but get a Program received signal SIGSEGV, Segmentation fault., in the fseek line

FILE *fp;
fp=open(blkname,O_RDONLY,0777);
fseek(fp, 0, SEEK_END);
size = ftell(fp);

fp returns a valind number (7);
also tried opening file with O_RDWR, and got same error.
blkname is a file with read write permissionas to everyone
i use open since it´s a binary file

any toughts?

That's because you are using open(), not fopen(). open returns a (most likely small) integer value, which is not a valid pointer (but not zero). Then fseek() will try to use that as a pointer.

--
Mats

and is fp != NULL at this point?

What is "blkname"?

--
Mats

if fp is 0x7, then it is NOT a FILE *, it's a filehandle. I bet that you are reading from the file with read(), not fread(). These are two different sets of file interfaces, one using an integer [essentially, and index into a table], the other using a POINTER to a FILE object.

--
Mats