Re: [boost] [range] boost::end("hello") is sub-optimal

From: Eric Niebler (eric_at_[hidden])
Date: 2005-12-31 10:58:44

Joe Gottman wrote:
> "Eric Niebler" <eric_at_[hidden]> wrote in message 
> news:43B6220B.4050408_at_boost-consulting.com...
> 
>>There is a bug in Boost.Range that is causing boost::end() to execute a
>>slower code path when called with a string literal. The type of "hello"
>>is char const [6], and end() should be O(1). Indeed, Boost.Range has
>>code to handle just this case, but it never gets called. The problem is
>>the way overload resolution happens between these two functions
>>
>>   template< typename T, std::size_t sz >
>>   const T* boost_range_end( const T (&array)[sz] )
>>
>>   const char* boost_range_end( const char* s )
>>
...
> 
> 
>    These two functions are not equivalent, since strlen("hello") equals 5 
> and  not 6.  Depending on what you are using the range for, you might or 
> might not want the '\0' at the end of the string to be part of the range.
> 

When I said, "Boost.Range has code to handle just this case" I meant 
that it handles arrays of char and wchar_t to account for the null 
termination. So these two functions *are* equivalent in that they both 
return the same value. The only difference is one is O(1) and the other 
is O(N).

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com