Matching Subexpressions (XML)

regex-iterator.cpp

/** In this example, the regular expression /<(.*)>(.*)</(\1)>/ searches for
 *  any number of any characters in angle brackets, any number of any characters
 *  in after the angle brackets, and then finally a forward slash followed by 
 *  any number of any characters, again in angle brackets. This thus forms the
 *  XML tags search expression.
 *
 */

#include <iostream>
#include <regex>
#include <string>


int main(int argc, char *argv[])
{
    const std::string data = "<Person>\n"
                             "    <FirstName>John</FirstName>\n"
                             "    <LastName>Meier</LastName>\n"
                             "</Person>\n";

    std::regex tagRegex("<(.*)>(.*)</(\\1)>");

    // Iterate over all matches
    auto pos = data.cbegin();
    auto end = data.cend();

    std::smatch match;

    for (; std::regex_search(pos, end, match, tagRegex); pos = match.suffix().first)
    {
        std::cout << "Match: " << match.str()  << "\n";
        std::cout << "  Tag: " << match.str(1) << "\n";
        std::cout << "Value: " << match.str(2) << "\n\n";
    }
}