Comment by 1718627440

I agree, that most practical programs will rely on unportable behaviour, but

> What printf() actaully does is implementation defined - what does "printing mean", does a console even exist? Maybe a user expects it to show graphical ascii/utf8 glyphs on a LCD display? Well, not every computer has that, so now what?

You can very well write a program, that doesn't make an assumption about any of those things. In fact you should, because the user is to be the arbiter of in what environment your program gets invoked and what it gets connected to. Writing a program that makes assumptions about the specific behaviour of stdout is going to be highly impractical and annoying and also violates the abstraction and interface that stdout is. This consideration isn't just valid for stdout, but also for any other interface your programs naturally interfaces with.

> Well, not every computer has that, so now what?

In the case stdout is not available or can't process your data it is going to return -1 and set errno and then you can deal with that.