Why is it possible to write() to STDIN?

Question

I have the following code:

int main()
{
    char str[] = \"Hello\\n\";
    write(0, str, 6);   // write() to STDIN
    return 0;
}

When I c

Answer 1

Because by default your terminal will echo stdin back out to the console. Try redirecting it to a file; it didn't actually write to stdout.