#include <iostream>

#include <sstream>

#include <string>



void validate(std::string const& a_str)

{

    std::cout << a_str << " is ";

    std::istringstream in(a_str);

    double val;

    if (in >> val && EOF == in.get()) std::cout << "valid\n";

    else std::cout << "invalid\n";

}



int main()

{

    validate("123.34ab");

    validate("123.34");

    return 0;

}