Re: [Boost-users] split_iterator<string::iterator> example

On 2/20/07, Pavol Droba wrote:

Meryl Silverburgh wrote:

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On 2/20/07, Pavol Droba wrote:

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Thanks, I did try just doing this cout << copy_rangestd::string(a) << endl; cout << copy_rangestd::string(b) << endl;

But I find out that 'integer_compare' just call once, and it is an empty string.

My input strings were "/1/11/2", "1/9/2". From your previous message, I understand the first time return an empty string, but I do expect integer_compare will call again and again like "1", "11", "2", "1", "9" ,"2".... But it did not happens.

Great, we are getting to the finish ;) There is just one slight problem, that I have overlooked in your code.

lexicographical_compare simply forwards the call to std::lexicographical_compare http://www.sgi.com/tech/stl/lexicographical_compare.html

So the given predicate (integer_compare) functions as *isless*. It means, that it should return true if the first argument is *less* then the second one. In case of equality it should return false.

In your case, lexicographical_compare stopped on the first tokens, since the predicate reported that one is less then other. No other comparison was necessary to get the result.

Try to change the result to false. You should be seeing the output from whole inputs.

Best regards, Pavol.

Pavol,

Thank you very much for your effort/time/help. Yes, I do see the output. But still one question, why my function integer_compare is being call 2 times for every sub-string?

my input strings are string s1("/1/11/2"), string s2("/1/9/3");

Here is my output:

calling integer_compare () () calling integer_compare () () calling integer_compare (1) (1) calling integer_compare (1) (1) calling integer_compare (11) (9) calling integer_compare (9) (11) calling integer_compare (2) (3) calling integer_compare (3) (2)

If you look better, you see that the arguments are reversed in the second call. because the interger_compare implements only '<' operation, we need actualy to call it twise to get ==.

Anyway, if you find lexicographical_compare insufficient in some regards, I'm sure you can now implement version that suits your needs.

I guess a bigger problem for me for using lexicographical_compare is I will get opposite result depends on the order of the input string: For example, if I have string s1("/1/9"), string s2("/1/9/3"); the compare will return true, but if I have string s1("/1/9/3"), string s2("/1/9"); it will return false. But for my case, I always want "/1/9" less than "/1/9/3" I guess I can compare the length of the 2 string and always put s1 to be the shorter one, and s2 to be the longer one. if there is an more efficient/cleaner idea, please let me know.

Regards, Pavol. _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users