I’ve been doing some exercises with printing to streams in C.
Today I’ve been a bit confused: as I understand in most implementations of the C standard library, the default behaviour of stdout is block buffered (or line buffered when connected to a terminal), but in my case it seems to be unbuffered.

For example, the following always prints before entering the infinite loop:

# include <stdio.h>
int main() {
    fputs("a", stdout);
    while (1);
    return 0;
}

I can force the behaviour I need by setting setvbuf(stdout, NULL, _IOFBF, 1024);, but I’m still confused by the default.

Is this expected behaviour when using gcc as provided by mingw-w64, or am I missing something?

Thanks!