#include <iostream>
#include <regex>
 
int main()
{
    std::regex pattern { "^a" };
    std::cout << "'^a' match with '': " << std::boolalpha << 
        std::regex_search("", pattern) << std::endl;
        
    std::cout << "'^a' match with 'abcd': " << std::boolalpha << 
        std::regex_search("abcd", pattern) << std::endl;
        
    std::cout << "'^a' match with 'dcba': " << std::boolalpha << 
        std::regex_search("dcba", pattern) << std::endl << std::endl;
        
    pattern = "a$";
    std::cout << "'a$' match with '': " << std::boolalpha << 
        std::regex_search("", pattern) << std::endl;
        
    std::cout << "'a$' match with 'abcd': " << std::boolalpha << 
        std::regex_search("abcd", pattern) << std::endl;
        
    std::cout << "'a$' match with 'dcba': " << std::boolalpha << 
        std::regex_search("dcba", pattern) << std::endl;
}