I am reading a peice of code which is at the following link: http://www.brpreiss.com/books/opus4/...00000000000000
The code is like this:
Object& StackAsLinkedLi st::Pop()
{
if(count==0)
throw domain_error("s tack is empty");
Object& const result=*list.Fi rst();
list.Extract(&r esult);
--count;
return result;
}
Does this code return a reference to local variable result? If this is the
case, then this code
has problem?
Thanks,
J.W. 6 1298
I am reading a peice of code which is at the following link: http://www.brpreiss.com/books/opus4/...CTION007123000
000000000000
The code is like this:
Object& StackAsLinkedLi st::Pop()
{
if(count==0)
throw domain_error("s tack is empty");
Object& const result=*list.Fi rst();
list.Extract(&r esult);
--count;
return result;
}
Does this code return a reference to local variable result? If this is
the case, then this code has problem?
Thanks,
J.W.
The list extract function is here: http://www.brpreiss.com/books/opus4/...00000000000000
On Aug 10, 11:12 am, Jianwei Sun <jsunnewsgr...@ gmail.comwrote:
I am reading a peice of code which is at the following link:http://www.brpreiss.com/books/opus4/...ECTION00712300...
The code is like this:
Object& StackAsLinkedLi st::Pop()
{
if(count==0)
throw domain_error("s tack is empty");
Object& const result=*list.Fi rst();
list.Extract(&r esult);
--count;
return result;
}
Does this code return a reference to local variable result? If this is the
case, then this code
has problem?
the function returns a reference (as required since the function's
return type is Object&).
The declaration for result is a const reference:
Object& const result(*list.Fi rst());
In effect, you aren't dealing with a temporary variable. Passing
references by value doesn't magicly allocate or deallocate its
referant.
Whether the code is correct is unknown to us. In particular, no-one
here knows what happens to result (the Object) during and after the
call to list.Extract(&r esult). We have no way of knowing how (or if)
the list is managing the Object lifetimes.
Hello Salt_Peter,
On Aug 10, 11:12 am, Jianwei Sun <jsunnewsgr...@ gmail.comwrote:
>I am reading a peice of code which is at the following link:http://www.brpreiss.com/books/opus4/...tml#SECTION007 12300...
The code is like this:
Object& StackAsLinkedLi st::Pop() { if(count==0) throw domain_error("s tack is empty"); Object& const result=*list.Fi rst(); list.Extract(& result); --count; return result; }
Does this code return a reference to local variable result? If this is the case, then this code has problem?
the function returns a reference (as required since the function's
return type is Object&).
The declaration for result is a const reference:
Object& const result(*list.Fi rst());
In effect, you aren't dealing with a temporary variable. Passing
references by value doesn't magicly allocate or deallocate its
referant.
Whether the code is correct is unknown to us. In particular, no-one
here knows what happens to result (the Object) during and after the
call to list.Extract(&r esult). We have no way of knowing how (or if)
the list is managing the Object lifetimes.
Hi, Peter,
The extact function is here: http://www.brpreiss.com/books/opus4/...00000000000000
If I get your meaning correclty, if the extract is deleting this node, then
this won't be correct.
If the extact doesn't delete this node, this will work fine.
Thanks,
J.W.
On Aug 10, 11:18*am, Jianwei Sun <jsunnewsgr...@ gmail.comwrote:
I am reading a peice of code which is at the following link: http://www.brpreiss.com/books/opus4/...CTION007123000
000000000000
The code is like this:
Object& StackAsLinkedLi st::Pop()
{
if(count==0)
throw domain_error("s tack is empty");
Object& const result=*list.Fi rst();
list.Extract(&r esult);
--count;
return result;
}
Does this code return a reference to local variable result? If this is
the case, then this code has problem?
Thanks,
J.W.
The list extract function is here:
http://www.brpreiss.com/books/opus4/...210000...-Hide quoted text -
- Show quoted text -
If we ignore that result is a const and the return type is non-const,
it would seem that the returned value (a reference) refers to an
object that has been deleted inside the Extract function. This, of
course, is wrong.
Hello An**********@gm ail.com,
On Aug 10, 11:18 am, Jianwei Sun <jsunnewsgr...@ gmail.comwrote:
>>I am reading a peice of code which is at the following link: http://www.brpreiss.com/books/opus4/...SECTION0071230 00 000000000000
The code is like this:
Object& StackAsLinkedLi st::Pop() { if(count==0 ) throw domain_error("s tack is empty"); Object& const result=*list.Fi rst(); list.Extract( &result); --count; return result; } Does this code return a reference to local variable result? If this is the case, then this code has problem? Thanks, J.W.
The list extract function is here:
http://www.brpreiss.com/books/opus4/...CTION005210000 ...- Hide quoted text -
- Show quoted text -
If we ignore that result is a const and the return type is non-const,
it would seem that the returned value (a reference) refers to an
object that has been deleted inside the Extract function. This, of
course, is wrong.
Thank you for verify, I just want to make sure I didn't miss something obvious
since the author who maintains
this tutorial is a very knowledgeable person and this book is a 5-star book
on amazon.com
Thanks,
J.W.
On 10 Aug, 19:56, Jianwei Sun <jsunnewsgr...@ gmail.comwrote:
Thank you for verify, I just want to make sure I didn't miss something obvious
since the author who maintains
this tutorial is a very knowledgeable person and this book is a 5-star book
on amazon.com
Thanks,
J.W
Still, I think the author's approach is inherently flawed. Why would
you want to implement your own data structures based on storing
pointers to an Object base class in C++? That's more like pre-generics
Java than idiomatic C++.
For C++, I recommend reading up on the STL instead.
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