[C] Why does it work like this?

[t1497f35]

Hi,
I was toying around using "write()" instead of "printf()" to write a string directly to STDOUT_FILENO and STDERR_FILENO, however, I noticed that "write" prints the string "hi" to the console even if I write it to STDIN_FILENO! Why? Imho it shouldn't print out anything in this case.



#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {

const char *buf = "hi\n";
ssize_t count = write(STDIN_FILENO, buf, strlen(buf));
if(count < 0) {
perror("Write");
}
exit(0);
}

[GeneralZod]

Writing to stdin is undefined behaviour, but the last answer here:

http://stackoverflow.com/questions/7383803/writing-to-stdin-and-reading-from-stdout-unix-linux-c-programming

gives a plausible explanation of why this would happen in a UNIX-y console.

[t1497f35]

Thanks, so I take it it's due to undefined behavior.