Re: [Boost-users] Using Boost string library

From: Boris Gubenko (Boris.Gubenko_at_[hidden])
Date: 2007-02-17 23:44:37

I may be overlooking something, and I hate to say it on the boost mailing list, 
but it seems to me that strcoll() C function does exactly what you need.

Thanks,
  Boris

----- Original Message ----- 
From: "Meryl Silverburgh" <silverburgh.meryl_at_[hidden]>
To: <boost-users_at_[hidden]>
Sent: Saturday, February 17, 2007 8:52 PM
Subject: Re: [Boost-users] Using Boost string library

> Thanks for your idea.
>
> I have cases like this:
>
> /1/1
> /1/2/3/2
>
> Since the first string /1/1 is smaller than the /1/2 (1 is < 2) of the
> /1/2/3/2, I should able to stop comparison by looking at the 4th
> character (/1/2) of '/1/2/3/2'.
>
> So for cases like that, I would like to stop as soon as i can tell one
> string is shorter than the other, instead of splitting the whole
> string.
>
>
>
> On 2/17/07, Pavol Droba <droba_at_[hidden]> wrote:
>> Hi,
>>
>> Meryl Silverburgh wrote:
>> > Hi,
>> >
>> > I need to compare 2 strings in this format (a integer separator by '/':
>> > /1/1
>> > /1/1/2
>> > /1/1/3
>> >
>> > so
>> > "/1/1" is less than "/1/1/2" and  "/1/1/2" is less than " "/1/1/3".
>> >
>> > Is there anything in Boost string library to help me to write such a 
>> > comparison?
>> > Is there a string iterator which literates base on the separator '/'?
>> > My idea is to find an iterator to loop thru the string based on
>> > separator '/'.
>>
>> There is a split_iterator which you can use. And there is a generic
>> lexicographical_compare function.
>>
>> I've got an idea that might work. But it is a little elaborate.
>> First, tokenize your string using split, but store the result to
>> vector<iterator_range>.
>>
>> Then define a comparison function, that will take the two
>> iterator_ranges and compare them. Note, that in this case, tha range
>> should hold an integer string.
>> Then simply use lexicographical_compare for the comparison.
>>
>>
>> vector<iterator_range> vec1;
>> split(vec, s1);
>> vector<iterator_range> vec2;
>> split(vec, s2);
>> if(lexicographical_compare(vec1, vec2, integer_compare))
>> {
>>         // s1 is less
>> }
>>
>> You can even throw away the vector, and directly create an
>> iterator_range from the split_iterator. This way you may spare some
>> unnecessary tokenization.
>>
>> typedef split_iterator<string::const_iterator> string_split;
>> iterator_range<string_split> r1(
>>         make_split_iterator(s1, is_any_of("/")), string_split())
>>
>> iterator_range<string_split> r2(
>>         make_split_iterator(s2, is_any_of("/")), string_split())
>>
>> if(lexicographical_compare(vec1, vec2, integer_compare))
>> {
>>         // s1 is less
>> }
>>
>> Best Regards,
>> Pavol.
>> _______________________________________________
>> Boost-users mailing list
>> Boost-users_at_[hidden]
>> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>>
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