Re: why are missing return statements from non-void functions not a

=?ISO-8859-1?Q?Daniel_Kr=FCgler?= <>
Fri, 30 Jul 2010 14:18:34 CST
On 30 Jul., 16:04, Goran Pusic <> wrote:

On Jul 29, 9:01 pm, Daniel Kr?gler <>

On 29 Jul., 17:05, Goran Pusic <> wrote:

Also, note that at the call site, you are not required to use return
value, so ultimately e.g. this:

int f(int g)
 if (g==5)
  return 7;
 // and else?

int main(int, const char*[])
  int i = f(5);
  f(6); // don't care about result, nor is there one, too!

will work.

Sorry, this is nonsense. The above code produces undefined
behavior, see 6.6.3/2:

"Flowing off the end of a function is equivalent to a return with
no value; this results in undefined behavior in a value-returning

Whoops... So this only worked on implementations I tried (blushes).
BTW, is the situation the same for C language?

It seems that C does support this situation, because this deviation of
specification is mentioned in the list of compatibility differences
between C and C++:

Change: It is now invalid to return (explicitly or implicitly) from a
which is declared to return a value without actually returning a value

Rationale: The caller and callee may assume fairly elaborate return-
value mechanisms for the return of class objects. If some flow paths
execute a return without specifying any value, the implementation
must embody many more complications. Besides, promising to
return a value of a given type, and then not returning such a value,
has always been recognized to be a questionable practice,
tolerated only because very-old C had no distinction between void
functions and int functions.

void strcpy(char* dest, const char* src)
  while (*dest++ = *src++);

into their C book, but he who wrote this today would probably be
called code red on in a code review. ;-)

I don't see anything wrong with that code.

Syntactically and functionally, me neither ;-). But my point was, to
be explicit, this is an exercise in term evaluation and operator
precedence that's IMO better left out of production code.

I meant my question serious, because I don't consider the
code-style used above as in any way harmful.

But I don't want to start a code-style war here, so I won't
participate in follow-ups of this particular point ;-)

HTH & Greetings from Bremen,

Daniel Kr?gler

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