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

From: Thore Karlsen (sid_at_[hidden])
Date: 2005-07-16 18:17:28

On Sat, 16 Jul 2005 18:46:33 +0200, Pavol Droba <droba_at_[hidden]>
wrote:

>> 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.

But is_iequal only tests for equality, it doesn't provide an ordering of
the characters. He's looking for something like is_iless, which I think
would be a nice addition too string_algo.

-- 
Be seeing you.