How to find file size without stdio library?

Asked Feb 28 '18 at 15:37

Active Sep 21 '18 at 06:09

Viewed 142 times

I am trying to find the size of a file without using stdio library.
This way (see below) works perfectly, but I can't find a way to make that work without stdio library.

int getfilesize(const char *filename){

   int size;
   FILE *f;

   f=fopen(filename, "rb");

   //pointer check
   if(f==NULL){
      return (-1);
   }

   fseek(f, 0, SEEK_END);
   size = ftell(f);
   fclose(f);

   return(size);
}

edited Sep 21 '18 at 06:09

Yunnosch

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asked Feb 28 '18 at 15:37

P.George

2

You could use [`stat`](https://linux.die.net/man/2/stat). – Jabberwocky Feb 28 '18 at 15:40
`fopen` and friends *are* in `stdio` library. – Eugene Sh. Feb 28 '18 at 15:40
2

@EugeneSh.he wants to do it _without_ stdio stuff – Jabberwocky Feb 28 '18 at 15:41
Hm. The most portable way would be *to use* `stdio`. – Eugene Sh. Feb 28 '18 at 15:42
you could use system primitives like `open` and `seek`, would that be OK? why would you want to avoid stdio? – Jean-François Fabre Feb 28 '18 at 15:44
1

@Jean-FrançoisFabre You can have branchiae instead :) – Eugene Sh. Feb 28 '18 at 15:44
I'm sorry, it's late :) – Jean-François Fabre Feb 28 '18 at 15:45
2

If you don't use stdio, the code may be less portable, but it's certainly doable. On a Unix system, the obvious solution is to use the `stat` system call. – Tom Karzes Feb 28 '18 at 15:45
`off_t size = lseek(fd, 0, SEEK_END);` or `off64_t size = lseek64(fd, 0, SEEK_END);` would be equivalent system calls, but using `stat` (also a system call) makes more sense. – ikegami Feb 28 '18 at 15:45
4

stat works fine on windows as well. but sounds like XY problem. – Jean-François Fabre Feb 28 '18 at 15:46
thanks guys. I also found a way to do it. I use lseek to go to the beginning of the file i want to find it's size and then use lseek to end and the return value is the number of bytes. thanks all for your time. – P.George Mar 01 '18 at 17:06
I think you need [Windows API](https://learn.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-getfilesizeex) or [Posix API](http://pubs.opengroup.org/onlinepubs/009695399/functions/stat.html). huh..? – Jan 13 '19 at 03:21

How to find file size without stdio library?

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