Help with C++ Boost::regex

Question

Hello everybody,

I'm trying to get all words inside a string using Boost::regex in C++.

Here's my input :

"Hello there | network - bla bla hoho"

using this code :

      regex rgx("[a-z]+",boost::regex::perl|boost::regex::icase);

      regex_search(input, result, rgx);

       for(unsigned int j=0; j<result.size(); ++j)
       {
         cout << result[j] << endl;
       }

I only get the first word "Hello".. whats wrong with my code ? result.size() returns 1.

thank you.

Answer 1

You're only searching for alphabetic characters, not spaces, pipes or hyphens. regex_search() probably just returns the first match.

Answer 2

You would need to capture any set of "[a-z]+" (or some other regex for matching "words") bound by spaces or string boundaries. You could try something like this:

^(\s*.+\s*)+$

In any event, this isn't really a boost::regex problem, it's just a regex problem. use perl or the bash shell (or any number of web tools) to get your regex figured out, then use in your code.

Answer 3

Perhaps you could try using repeated captures with the following regex "(?:([a-z]+)\\b\\s*)+".

Answer 4

regex_search only finds the first match. To iterate over all matches, use regex_iterator

Answer 5

To match words, try this regex:

regex rgx("\\<[a-z]+\\>",boost::regex::perl|boost::regex::icase);

According to the docs, \< denotes the start of a word and \> denotes the end of a word in the Perl variety of Boost regex matching.

I'm afraid someone else has to explain how to iterate the matches. The Boost documentation makes my brain hurt.