#include <iostream>
#include <string>
#include <regex>
 
int main()
{
    std::regex pattern { "." };
    std::cout << "'.' match with '': " << std::boolalpha << 
        std::regex_match("", pattern) << std::endl;
        
    std::cout << "'.' match with 'a': " << std::boolalpha << 
        std::regex_match("a", pattern) << std::endl;
        
    std::cout << "'.' match with 'ab': " << std::boolalpha << 
        std::regex_match("ab", pattern) << std::endl;
        
    pattern = "abc";
    std::cout << "'abc' match with 'abc': " << std::boolalpha << 
        std::regex_match("abc", pattern) << std::endl;
        
    std::cout << "'abc' match with 'a$c': " << std::boolalpha << 
        std::regex_match("a$c", pattern) << std::endl;
        
    pattern = "a.c";
    std::cout << "'a.c' match with 'abc': " << std::boolalpha << 
        std::regex_match("abc", pattern) << std::endl;
        
    std::cout << "'a.c' match with 'a$c': " << std::boolalpha << 
        std::regex_match("a$c", pattern) << std::endl;
}