• bearophile (5/5) Jan 20 2009 I post this here, but if later I see it fit I may post something in the ...
• Bill Baxter (3/5) Jan 20 2009 What does it return now? I always assumed returned zero for void main.
• bearophile (5/7) Jan 20 2009 Me too.
• Jarrett Billingsley (4/9) Jan 20 2009 I've only ever seen void mains return 0. I think they used to return
• Steven Schveighoffer (45/50) Jan 20 2009 A test:
• Jarrett Billingsley (3/4) Jan 20 2009 Ha!
• Denis Koroskin (11/16) Jan 20 2009 Yes (but not always), even though specs clearly say that void functions ...

bearophile <bearophileHUGS lycos.com> writes:

I post this here, but if later I see it fit I may post something in the main D
group too.

D allows to have the main() function of type void too. In such case I'd like
the program return 0 by default. If people agrees, this can become a feature
request.

A question: when D automatically adds some padding to a struct, is such unused
space guaranteed to be initialized to a default constant value, like zero?

Bye,
bearophile

Bill Baxter <wbaxter gmail.com> writes:

On Tue, Jan 20, 2009 at 11:15 PM, bearophile <bearophileHUGS lycos.com> wrote:
 I post this here, but if later I see it fit I may post something in the main D
group too.

 D allows to have the main() function of type void too. In such case I'd like
the program return 0 by default. If people agrees, this can become a feature
request.

What does it return now?  I always assumed returned zero for void main.

--bb

bearophile <bearophileHUGS lycos.com> writes:

Bill Baxter:

 What does it return now?

A random int, I presume.


I always assumed returned zero for void main.<

Me too.

Bye,
bearophile

"Jarrett Billingsley" <jarrett.billingsley gmail.com> writes:

On Tue, Jan 20, 2009 at 10:25 AM, bearophile <bearophileHUGS lycos.com> wrote:
 Bill Baxter:

 What does it return now?

 A random int, I presume.


I always assumed returned zero for void main.<

 Me too.

I've only ever seen void mains return 0.  I think they used to return
random ints but that was fixed long ago.  Maybe it's different on
Linux?

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

"bearophile" wrote
I post this here, but if later I see it fit I may post something in the 
main D group too.

 D allows to have the main() function of type void too. In such case I'd 
 like the program return 0 by default. If people agrees, this can become a 
 feature request.

A test:
[steves localhost testing]$ cat testmainreturn.d
void main()
{
    return 1;
}
[steves localhost testing]$ cat testmainreturn2.d
void main()
{
}
[steves localhost testing]$ dmd testmainreturn.d
[steves localhost testing]$ dmd testmainreturn2.d
[steves localhost testing]$ ./testmainreturn
[steves localhost testing]$ echo $?
1
[steves localhost testing]$ ./testmainreturn2
[steves localhost testing]$ echo $?
0
[steves localhost testing]$ dmd | grep "Digital Mars D"
Digital Mars D Compiler v1.038
[steves localhost testing]$

disassembly:
[steves localhost testing]$ obj2asm testmainreturn.o
...
_Dmain:
                push    EBP
                mov     EBP,ESP
                mov     EAX,1
                pop     EBP
                ret
.text._Dmain    ends
...
[steves localhost testing]$ obj2asm testmainreturn2.o
...
_Dmain:
                push    EBP
                mov     EBP,ESP
                xor     EAX,EAX
                pop     EBP
                ret
.text._Dmain    ends
...

So it appears it returns 0 unless you return something else (!)

-Steve

"Jarrett Billingsley" <jarrett.billingsley gmail.com> writes:

On Tue, Jan 20, 2009 at 12:21 PM, Steven Schveighoffer
<schveiguy yahoo.com> wrote:
 So it appears it returns 0 unless you return something else (!)

Ha!

Denis Koroskin <2korden+dmd gmail.com> writes:

Jarrett Billingsley Wrote:

 On Tue, Jan 20, 2009 at 12:21 PM, Steven Schveighoffer
 <schveiguy yahoo.com> wrote:
 So it appears it returns 0 unless you return something else (!)

 
 Ha!

Yes (but not always), even though specs clearly say that void functions
evaluate return values and discard them.

IIRC, this one returns 0:

void main() { 
    return new Object();
}

while this one returns an object address:

void foo() { return new Object(); }

void main() {
    return foo();
}