CODEWITHSUNDEEP
c++regexboostlambda
johnco3
johnco3

Reputation: 2642

iterating over boost regex_iterator results

I need some help to understand how to iterate over the search results from a boost::sregex_iterator. Basically I am passing in a ';' delimited set of IP addresses from the command line, and I would like to be able to process each IP address in turn using a boost::sregex_iterator.

The code below demonstrates what I am trying to do and also shows a workaround using the workingIterRegex - however the workaround limits the richness of my regular expression. I tried modifying the nonworkingIterRegex however it only returns the last IP address to the lambda.

Does anyone know how I can loop over each IP address individually without having to resort to such a hacked and simplistic workingIterRegex.

I found the following http://www.cs.ucr.edu/~cshelton/courses/cppsem/regex2.cc to show how to call the lambda with the individual sub matches.

I also used the example in looping through sregex_iterator results to get access to the sub matches however it gave similar results.

After using the workingIterRegex the code prints out the IP addresses one per line

#include <string>
#include <boost/regex.hpp>
...
std::string errorMsg;
std::string testStr("192.168.1.1;192.168.33.1;192.168.34.1;192.168.2.1");
static const boost::regex nonworkingIterregex (
    "((\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3});?)+",
    boost::regex_constants::icase);
boost::smatch match;
if (boost::regex_match(testStr, match, nonworkingIterregex)) {            
    static const boost::regex workingIterRegex("[^;]+");
    std::for_each(boost::sregex_iterator(
        begin(iter->second), end(iter->second), workingIterRegex),
        boost::sregex_iterator(),
        [](const boost::smatch &match){ 
            std::cout << match.str() << std::endl;
        }
    );

    mNICIPAddrs = UtlStringUtils::tokenize(iter->second, ";");
    std::string errorMsg;
} else {
    errorMsg = "Malformed CLI Arg:" + iter->second;
}
if (!errorMsg.empty()) {
    throw std::invalid_argument(errorMsg);
}
...

After some experimentation I found that the following worked - but I am not sure why the c

Upvotes: 2

Views: 1250

Answers (1)

l&#39;L&#39;l
l&#39;L&#39;l

Reputation: 47169

Try using your regex expression like this:

(\\d{1,3}\\.){3}(\\d{1,3})

Upvotes: 1

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