Bad file descriptor

Question

I\'m learning about file descriptors and I wrote this code:

#include 
#include 
#include 
#include          


        

Answer 1

According to the open(2) man page:

The argument flags must include one of the following access modes: O_RDONLY, O_WRONLY, or O_RDWR.

So yes, as suggested by others, please change your open to open("output", O_CREAT|O_WRONLY, 0777));. Use O_RDWR if you need to read from the file. You may also want O_TRUNC -- see the man page for details.