Issues with for loops

[twoeyedhuman1111]

I have this function that looks like this:

bool is_descendant_of(const TreeT& ancestor) // line 316
{
for (TreeT* t = this; t; t = t->_parent) // line 318
if (t == &ancestor) // line 319
break; // line 320

return (t != NULL); // line 322
}

When I compile it with g++, I get this error message saying:

tree.cpp: In member function `bool gems::tree<T,
Alloc>::is_descendant_of(const
gems::tree<T, Alloc>&)':
tree.cpp:322: error: name lookup of `t' changed for new ISO `for'
scoping
tree.cpp:318: error: using obsolete binding at `t'

I'm not sure why it says this. I tried taking the t out of the return
statement and replacing t's value with a temporary variable, but that
didn't work either. I think it has do with the 318'th line.

[Mike Wahler]

"twoeyedhuman1111" <tw**************@gmail.com> wrote in message
news:11**********************@f14g2000cwb.googlegr oups.com...

I have this function that looks like this:

bool is_descendant_of(const TreeT& ancestor) // line 316
{
for (TreeT* t = this; t; t = t->_parent) // line 318
if (t == &ancestor) // line 319
break; // line 320

return (t != NULL); // line 322
}

When I compile it with g++, I get this error message saying:

tree.cpp: In member function `bool gems::tree<T,
Alloc>::is_descendant_of(const
gems::tree<T, Alloc>&)':
tree.cpp:322: error: name lookup of `t' changed for new ISO `for'
scoping
The scope of the object 't' is that of the 'for' loop.
When the loop terminates, 't' is destroyed. Thus the
expression 't != NULL' is not valid, because there's
no object 't' in existence at that point.
tree.cpp:318: error: using obsolete binding at `t'

I'm not sure why it says this. I tried taking the t out of the return
statement and replacing t's value with a temporary variable, but that
didn't work either. I think it has do with the 318'th line.

Don't guess. Read a good (current) C++ text. See www.accu.org
for book reviews.

-Mike

[akarl]

twoeyedhuman1111 wrote:

I have this function that looks like this:

bool is_descendant_of(const TreeT& ancestor) // line 316
{
for (TreeT* t = this; t; t = t->_parent) // line 318
if (t == &ancestor) // line 319
break; // line 320

return (t != NULL); // line 322
}

When I compile it with g++, I get this error message saying:

tree.cpp: In member function `bool gems::tree<T,
Alloc>::is_descendant_of(const
gems::tree<T, Alloc>&)':
tree.cpp:322: error: name lookup of `t' changed for new ISO `for'
scoping
tree.cpp:318: error: using obsolete binding at `t'

I'm not sure why it says this. I tried taking the t out of the return
statement and replacing t's value with a temporary variable, but that
didn't work either. I think it has do with the 318'th line.

I'd write it as

bool is_descendant_of(const TreeT &ancestor)
{
TreeT *t = this;

while ((t != NULL) && (t != &ancestor)) { t = t->_parent; }
return t == &ancestor;
}
August

[red floyd]

twoeyedhuman1111 wrote:

I have this function that looks like this:

bool is_descendant_of(const TreeT& ancestor) // line 316
{
for (TreeT* t = this; t; t = t->_parent) // line 318
if (t == &ancestor) // line 319 return true;
return false; }

[twoeyedhuman1111]

Wow, I can't believe I didnt see that. I look at it now and say omg
what am I thinking.

Thank you very much for pointing this out