C++ Regular Expressions with Boost Regex

Question

I am trying to take a string in C++ and find all IP addresses contained inside, and put them into a new vector string.

I\'ve read a lot of documentation on regex, b

Answer 1

#include 
#include 
#include 
typedef std::string::const_iterator ConstIt;

int main()
{
    // input text, expected result, & proper address pattern
    const std::string sInput
    (
            "192.168.0.1 10.0.0.255 abc 10.5.1.00"
            " 1.2.3.4a 168.72.0 0.0.0.0 5.4.3.2"
    );
    const std::string asExpected[] =
    {
        "192.168.0.1",
        "10.0.0.255",
        "0.0.0.0",
        "5.4.3.2"
    };
    boost::regex regexIPs
    (
        "(^|[ \t])("
        "(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])[.]"
        "(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])[.]"
        "(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])[.]"
        "(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])"
        ")($|[ \t])"
    );

    // parse, check results, and return error count
    boost::smatch what;
    std::list ns;
    ConstIt end = sInput.end();
    for (ConstIt begin = sInput.begin();
                boost::regex_search(begin, end, what, regexIPs);
                begin = what[0].second)
    {
        ns.push_back(std::string(what[2].first, what[2].second));
    }

    // check results and return number of errors (zero)
    int iErrors = 0;
    int i = 0;
    for (std::string & s : ns)
        if (s != asExpected[i ++])
            ++ iErrors;
    return iErrors;
}