Let the Compiler Do the Work

Re:Let the Compiler Do the Work by oefrha on Tuesday January 07, 2020 @01:54PM (#21983266)

When you decide to define new variables you have already decided to write more than just an expression (which by definition can’t contain a statement), so “you can’t do that for...” is a moot point. And since it’s not an expression, it’s not gonna appear as its own argument, unless you’re using more advanced substituting a whole block trick which is not what the do while(0) idiom is for.

[ Parent | on HN ]

Re:Let the Compiler Do the Work by simias on Tuesday January 07, 2020 @05:19PM (#21985706)

I can't make sense of what you're saying. See the page I linked in my previous post for an example of what we're talking about: https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html

    #define maxint(a,b) \
      ({int _a = (a), _b = (b); _a > _b ? _a : _b; })

>Note that introducing variable declarations (as we do in maxint) can cause variable shadowing [...] this example using maxint will not [produce correct results]:

    int _a = 1, _b = 2, c;
    c = maxint (_a, _b);

[ Parent | on HN ]

Re:Let the Compiler Do the Work by oefrha on Tuesday January 07, 2020 @08:54PM (#21987468)

That’s a GNU C extension. I don’t write non-portable code like that. (Okay, I didn’t notice the link in your previous post, so I was basically replying to the wrong thing.)

[ Parent | on HN ]