Re: Segmentation fault

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sat, 4 Oct 2008 00:54:52 -0700 (PDT)
Message-ID:
<90b75969-f9e2-4ceb-b595-34a72e1432d5@34g2000hsh.googlegroups.com>
On Oct 3, 5:08 pm, Zeppe <ze...@remove.all.this.long.comment.yahoo.it>
wrote:

Rolf Magnus wrote:

Ioannis Vranos wrote:

The following code sometimes runs OK in my system, sometimes it produces
a segmentation fault (access to inaccessible memory). I filled it as a
bug of GCC, but am posting it here in case I did something wrong.


I think you did.


Of course he did. If I can suggest a good metric to the OP, when your
program crashes, well, *usually* it's the programmer's fault, not the
compiler's ;)

SomeClass::SomeClass(const SomeClass &):vec(VectorSize)
{
     using namespace std;

     for(TypeVector::size_type i= 0; i< vec.size(); ++i)
         vec[i]= rand();

     sort(vec.begin(), vec.end());
}


Here, the object changes the value used for operator< when copied, which is
likely to lead to problems with sorting your container of SomeClass
objects.


More in general, for all the containers and all the iterators defined
over a type T, the type T has to be (among other things)
CopyConstructible, that is, given an object t1 of type T,

T t(t1);

means that t and t1 are equivalent (t == t1). If your copy constructor
doesn't satisfy this rule, the algorithms (containers, pointers, etc)
behaviour is undefined.

Best wishes,

Zeppe

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