#include<regex>
#include<string>

int main() {
    std::string text = "the integer a equals 353, whereas b = 12";
    
    std::regex pattern("the integer a equals (\\d+), whereas b = (\\d+)");
    std::smatch match;
    
    if(std::regex_match(text, match, pattern)) {
        std::string a = match[1];  // acquires value "353"
        std::string b = match[2];  // acquires value "12"
    }

    return 0;
}