Re: Regarding assignment to struct

On 02/05/2025 20:34, Lew Pitcher wrote:

Back in the days of K&R, Kernighan and Ritchie published an addendum
to the "C Reference Manual" titled "Recent Changes to C" (November 1978)
in which they detailed some differences in the C language post "The
C Programming Language".
 The first difference they noted was that
   "Structures may be assigned, passed as arguments to functions, and
    returned by functions."
  From what I can see of the ISO C standards, the current C language
has kept these these features. However, I don't see many C projects
using them.

I use these features regularly.  I have no problem passing structs around if that is the convenient way to structure the code.
Some people mistakenly think that it is very inefficient, in comparison to passing around pointers to structs (which is the usual alternative). There are circumstances where you might end up with an extra struct and an extra copy, but unless you are dealing with very big structs and otherwise very fast functions, it's unlikely to be significant.  Modern ABI's support passing small structs around in registers, and bigger structs get passed around using hidden pointers - using the structs in your code, rather than pointers to structs, makes the code clearer, safer, and gives the optimiser more information for better static analysis and code generation.

 I have a project in which these capabilities might come in handy; has
anyone had experience with assigning to structures, passing them as
arguments to functions, and/or having a function return a structure?
 Would code like
   struct ab {
     int a;
     char *b;
   } result, function(void);
    if ((result = function()).a == 10) puts(result.b);
 be understandable, or even legal?
 

I'd immediately reject any code that mixes declaration of a variable and a function in the same declaration.  I'd immediately reject any code that defines a type and declares a function in one shot.  I'd question code that defines a type and a variable in one go.  But that's my way of coding - other people have different rules, and your declarations are legal.
Personally, I'd have :
typedef struct {
int a;
char * b;
} ab;
ab result;
ab function(void);

(Obviously "ab" would not be a likely name in real code.)
Once the type "ab" is defined, I am quite happy making variables of it, assigning them, and using it for function parameters and return types.