I think the history of this is that these operations were common with assembly programmers, so when C came along, these were included in the language to allow these developers to feel they weren't leaving lots of performance behind.

Look at the addressing modes for the PDP-11 in https://en.wikipedia.org/wiki/PDP-11_architecture and you'll see you can write (R0)+ to read the contents of the location pointed to by R0, and then increment R0 afterwards (so a post increment).

Back in the day, compilers were simple and optimisations weren't that common, so folding two statements into one and working out that there were no dependencies would have been tough with single pass compilers.

You could argue that without such instructions, C wouldn't have been embraced quite so enthusiastically for systems programming, and the world would have looked rather different.

Python recently went the other way and added an assignment expression. I actually wish more languages would go further and add statement expressions instead of having to imitate them with IIFEs.

C just wouldn't be C without things like a[i++]

Those things are for pointer golf and writing your entire logic inside the if statement.

Both are favorite idioms of C developers. And they are ok if done correctly, clearer than the alternative. They are also unnecessary in modern languages, so those shouldn't copy it (yeah, Python specifically).

int d = foo ? bar() : baz();

I think if anything people have been leaning more and more into expressions over statements, because when everything is an expression you end up being able to walk the gradient of complexity a bit more nicely than when you end up with a thing that just has to be broken down to a bunch of statements.

In any language where the practice of iteration isn't achieved via C-style for-loops, having an operator devoted to increment just doesn't make sense (let alone four operators, for each of pre/post-increment/decrement). This is one of those backwards things that just needs to be chucked in the bin for any language developed post-2010.

Wenn wouldn't have pearls like while (dst++ = src++);