Hacker News new | ask | show | jobs
by rocketrascal 36 days ago
You can't make any useful software in "Portable C" - or any portable language for that matter.

Side effects matter, and they are always non-portable/implementation defined/dependent on the hardware.

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?
2 comments
eru 35 days ago
> You can't make any useful software in "Portable C" - or any portable language for that matter.

Have you heard of Java or even Python or JavaScript?

> Side effects matter, and they are always non-portable/implementation defined/dependent on the hardware.

Granted. But how does the need for implementation defined excuse undefined behaviour?

> What printf() actaully does is implementation defined [...]

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

The standard can be written conditionally: 'if the computer has display, printf shall show something.'

link
1718627440 36 days ago
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.

link