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

20 Feb 2007

      On 2/20/07, Pavol Droba <droba@topmail.sk> wrote:
...
Hi,
Meryl Silverburgh wrote:
...
On 2/20/07, Pavol Droba <droba@topmail.sk> wrote:
...
...
Pavol,
Thank for your help. I thought you said 'The question marks can be
substituted by
string_split::value_type'. In one of our previous exchange.
That is why I am using 'string_split::value_type' not
'iterator_range<string::iterator>'
Sorry if I mis-understand what you teach me.
No worries.
There is no problem with using string_split::value_type. It is just
a typedef to iterator_range<string::iterator>. In your code, you
misplaced it with string_split itself.
I change the integer_compare class to use  iterator_range<string::iterator>&.
And I am trying to loop thru the iterator_range inside the function()
of integer_compare:
bool operator() (const  iterator_range<string::iterator>& a,
const   iterator_range<string::iterator>& b) {
              cout << "calling integer_compare " << endl;
// expect to print out "", "1", "1", "2" for a string of "/1/1/2"
              for (string::iterator sitr = a.begin(); sitr != a.end(); sitr++) {
cout << copy_range<std::string>(*sitr) << endl;
}
               return true;
       }
Please, see the iterator_range documentation:
http://www.boost.org/libs/range/doc/utility_class.html#iter_range
Although you changed the names of parameters, you are still using
iterator_range as if it was a split_iterator.
copy_range copies a *range* to a given container. when you dereference
a string::iterator, you will not get a *range*, rather a single character.
Instead of "for" loop you should use just
cout << copy_range<std::string>(a) << endl;
Thanks, I did try just doing this
cout << copy_range<std::string>(a) << endl;
cout << copy_range<std::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.

class integer_compare {
public:
    //   bool operator() (const string_split::value_type &a, const
//string_split::value_type &b) {

	bool operator() (const 	iterator_range<string::iterator>& a,

	const 	iterator_range<string::iterator>& b) {
		cout << "calling integer_compare " << endl;

		cout << copy_range<std::string>(a) << endl;
		cout << copy_range<std::string>(b) << endl;
		/*
		for (string::iterator sitr = a.begin(); sitr != a.end(); sitr++) {

			cout << copy_range<std::string>(*sitr) << endl;

		}*/
               return true;
       }

};

int main(int argc, char **argv) {
       cout << "hello world" << endl;

       string s1("/1/11/2");
       string s2("/1/9/3");

       iterator_range<string_split> r1(
                       make_split_iterator(s1,
token_finder(is_any_of("/"))), string_split());

               iterator_range<string_split> r2(
                       make_split_iterator(s2,
token_finder(is_any_of("/"))), string_split());

               if(lexicographical_compare(r1.begin(), r1.end(),

                               r2.begin(), r2.end(), integer_compare()))
               {
                       cout << " s1 is less " << endl;
               } else {
                       cout << " s2 is less " << endl;
               }

}
...
Regards,
Pavol.
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