From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Krzysztof Czainski
Sent: Friday, December 10, 2010 9:00 AM
To: boost-users@lists.boost.org
Subject: Re: [Boost-users] Range_iterator - char* - reverse

 

      char *s = "abcdefg";

     

      iterator_range<char*> ir( &s[0], &s[ strlen(s) ] );

      char *cp;

 

      boost::range_reverse_iterator< char*>::type irb = boost::rbegin( ir );

      boost::range_reverse_iterator< char*>::type ire = boost::rend( ir );

 

      for (; irb != ire; ++irb)

      {

            cout << "reverse cp [" << *irb << "]\n";

      }

 

This works like a charm – both in fwd and reverse traversal.

 

However, what I want is – in reverse traversal also, I want to use the same pointer (“cp” in this case). In other words, I want to use the same pointer to traverse in both directions.

Here’s what I want to be able to write, but get a compile error with both attempts and I was wondering if you could help.

 

Option  1:

for (cp = boost::rbegin(ir); cp != boost::rend(ir); ++cp)

{

      cout << "cp reverse in ri [" << *cp << "]\n";

}

 

Option 2:

while( cp != ire )

{

  //Do something

  cp++

}