not using the return value

[Gary Wessle]

Hi

I read an example provided by Big Bucks Inc. no how to use their
library. in it they have some thing like

string doit(){ /* ... */ cout << "doit called" << endl; }

int main(){
doit();
}
how can this be correct?
should not doit() return void? and if not, what am I missing?

thanks

[Noah Roberts]

Gary Wessle wrote:

Hi

I read an example provided by Big Bucks Inc. no how to use their
library. in it they have some thing like

string doit(){ /* ... */ cout << "doit called" << endl; }

int main(){
doit();
}
how can this be correct?
should not doit() return void? and if not, what am I missing?

Or it should actually return something. It is perfectly ok to ignore a
return value but not to not return a value from a non-void function.

[Victor Bazarov]

Gary Wessle wrote:

I read an example provided by Big Bucks Inc. no how to use their
library. in it they have some thing like

string doit(){ /* ... */ cout << "doit called" << endl; }

int main(){
doit();
}
how can this be correct?
should not doit() return void? and if not, what am I missing?

If a function returns something and another function makes no use
of that, it's perfectly OK. The return value is simply discarded
(and if it's a temporary, it's destroyed).

What seems to be dangerous (although not necessarily wrong) here
is that while 'doit' is declared to return 'string', it has not
'return' statement. I guess we aren't supposed to care about the
fact that your program as posted doesn't define 'string' or 'cout'
or 'endl'...

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Salt_Peter]

Gary Wessle wrote:

Hi

I read an example provided by Big Bucks Inc. no how to use their
library. in it they have some thing like

string doit(){ /* ... */ cout << "doit called" << endl; }

int main(){
doit();
}
how can this be correct?
should not doit() return void? and if not, what am I missing?

thanks

technically, doit() needs to return whatever its return-type is (which
was not shown above). The context in which doit() is called - in this
case: main() - is not obliged in any way to capture the returned value.
The same goes with int main() itself. The operating system is not
required to do anything with its return either.
These returns, if not captured are simply dropped.

[Steve Pope]

Noah Roberts <ro**********@gmail.comwrote:

>It is perfectly ok to ignore a
return value but not to not return a value from a non-void function.

Whatever happened to the days when the last expression evaluated
during a function became the return value, if no "return" was used?

Steve

[Jack Klein]

On Sat, 9 Dec 2006 02:33:27 +0000 (UTC), sp*****@speedymail.org (Steve
Pope) wrote in comp.lang.c++:

Noah Roberts <ro**********@gmail.comwrote:

It is perfectly ok to ignore a
return value but not to not return a value from a non-void function.

Whatever happened to the days when the last expression evaluated
during a function became the return value, if no "return" was used?

That was never part of the C or C++ language. Even in the days of
implicit int in C, when unprototyped functions were assumed to return
an int, what do you think would happen if the last expression
evaluated during a function yielded a floating point type?

--
Jack Klein
Home: http://JK-Technology.Com
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[Steve Pope]

Jack Klein <ja*******@spamcop.netwrote:

>On Sat, 9 Dec 2006 02:33:27 +0000 (UTC), sp*****@speedymail.org (Steve

>Whatever happened to the days when the last expression evaluated
during a function became the return value, if no "return" was used?

>That was never part of the C or C++ language. Even in the days of
implicit int in C, when unprototyped functions were assumed to return
an int, what do you think would happen if the last expression
evaluated during a function yielded a floating point type?

What I think probably happened back then was that a particular
register large enough to hold any value that a old-style C function
could return (char, int, long, float, pointer, double -- i.e. a
64 bit register) was loaded with the return value or final expression
value, and then a "return from subroutine" instruction was used.

C had a certain compactness to it but it's
nice to not have to think about low-level stuff anymore.

Steve