Re: VS 2005 compiler died on this recursive template

From:

=?ISO-8859-1?Q?Daniel_Kr=FCgler?= <daniel.kruegler@googlemail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Tue, 16 Mar 2010 04:44:48 CST

Message-ID:

<5c88323f-14d0-4893-9bb1-22f40474a959@19g2000yqu.googlegroups.com>

On 16 Mrz., 05:25, Alex <alexey.d.zait...@gmail.com> wrote:

template <int i>
struct Factorial
{
enum { N = i<=0? 1 : i*Factorial<i-1>::N };};

//template<> struct Factorial<0> { enum { N = 1 }; };
// IF uncoment ? working fine
void main() {
int factorial=Factorial<3>::N;
}

1) The main function must have an int return type.

2) The specialization is required. It doesn't help that
you check "i <= 0" inside the primary template to
prevent the compiler from instantiating Factorial<i-1>
because the kind of expression it occurs in, naming
a member via qualification ("Factorial<i-1>::N"), does
require an instantiation of the class Factorial<i-1>
even though the branch will not be entered.

But *if* it instantiates Factorial<i-1>, this is a never-
ending story without any explicit specialization.

HTH & Greetings from Bremen,

- Daniel

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