Ej7Chapter20C++

#include <iostream>
#include <vector>

int main(void)
{
    char* p = NULL;
    std::string s1(p);
    std::cout << s1 << std::endl;

    const char input[] = "Hola";
    std::string s2(input);
    std::cout << s2.at(4) << std::endl;

    std::vector<char> charvec(5, 'a');
    std::string s3(&charvec[0], 5);
    std::cout << s3 << std::endl;

    std::string s4 (std::string::npos, 'a');
    std::cout << s4 << std::endl;

    return EXIT_SUCCESS;
}