Re: [Boost-users] case insensitive less_than string comparison

From: Pavol Droba (droba_at_[hidden])
Date: 2005-07-16 11:46:33

Hi,

On Sat, Jul 16, 2005 at 03:02:11PM +0200, Matthias Kaeppler wrote:
> Hi,
> 
> I am aware that string_algo has an if_iequal functor. Is there also an 
> equivalent for a less-than comparison? I have to compare strings 
> ignoring the case but taking locales into account.
> Right now I'm calling boost::algorithm::to_lower on two copies of the 
> original strings. I'm not so sure if this is very efficient when I'm 
> comparing thousands of strings.
> 
> Here's the functor as it is now:
> 
>      struct FileLessNameA
>          : std::binary_function<const File&,const File&,bool> {
>          bool operator() (const File& lhs, const File& rhs) const {
>              std::string path1( lhs.get_name().c_str() );
>              std::string path2( rhs.get_name().c_str() );
>              boost::algorithm::to_lower( path1 );
>              boost::algorithm::to_lower( path2 );
>              return path1 < path2;
>          }
>      };
> 

There is no such a function in string_algo lib. But you can easily use 
std::lexicographical_compare.

There is a variant with a custom comparison predicate. For that you can use
boost::is_iequal defined in boost/algorithm/string/compare.hpp.

Best regards,
Pavol.