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

int main()
{
    std::regex nice_number(R"(\d+(,?\d\d\d)*\.?\d*)");
    std::string some_values("12,345,758.98 is a long number. "
            "33 is a short one. 45,12,34 isn't really one number. 1.3 is."
            "0.2 is. and so forth.");

    std::for_each(std::sregex_iterator(
                begin(some_values), end(some_values), nice_number),
            std::sregex_iterator(),
            [](auto&& match) {
                std::cout << "Number: " << match.str() << '\n';
            });
}