[harry8]

    int pop_int () 
    {
      int x = *stack; 
      --stack;
      return x;
    }

    void push_int(int x)
    {
      ++stack;
      *stack = x;
    }

Genunine questions:

- Is this worse? - How does the state get inconsistent?

[saagarjha]

For one it’s three and two lines for what is two logical operations. I assume the “inconsistent state” is the time between the lines where the stack is not truly in the right state-many people prefer to preserve their invariants as much as possible.

[harry8]

it will produce indistinguishable assembly language, no?

[saagarjha]

The use of that construct is mainly a stylistic choice. On any compiler from this millennium there should be no difference in the code that it produces.

[harry8]

Yep so if we're going with style I'm very happy with the functions dashed off there. Nobody will confuse those even when very, very tired (similar effect on the brain to being drunk). There is zero difference in the generated output. Calling those functions tells you exactly what they are and what they do. Vertical space is not an issue at all with 3 line functions.

Relying on post-increment? Make sure it's a one line block that is totally unbraced with only single letter variable names if you do it because otherwise it's just faux-macho C and that's /weak/.

[saagarjha]

> Make sure it's a one line block that is totally unbraced with only single letter variable names if you do it because otherwise it's just faux-macho C and that's /weak/.

I think you're projecting. The point being made was that when you're writing a simple stack (as you often might do in C, since the standard library and the language itself conspire against providing you one) and you don't have the overhead to write multiple functions to wrap it up (vertical space is an issue when you make more than one of these–trust me, I used to write Java and every thing about it was just a papercut in verbosity), the post- and pre-increment versions are concise, idiomatic, and–to be honest–more clear simply because they use the operators in the way that they are meant to be used. I can glance at them and see, OK, this one gives me whatever the stack is pointing to and then makes it point to the next element; this one first moves the pointer to the next element (which is free) and sets it. All in one line. There's nothing to show off here, this is just how you write C; those operators exist for exactly this purpose (and IMO single letter variable names are generally only a good idea in the smallest of scopes, and I personally use braces even when optional).

[harry8]

Sorry no. That's not for you in particular that's just a general comment on macho C, which I think we've all seen.

    int abc(int a, int b, int c)
    {

    }

I can do postincrement. I learned C the macho way. We all still have to read that crap. Now I know better when I'm writing it. I strongly disagree that

   a = *stack--;
   *++stack = b

is better in any way beyond "I'm a macho C guy" than

    a = pop_int();
    push_int(b);

https://en.wikipedia.org/wiki/Duff%27s_device

It's fun when you first see it. Sure.