EOSIO Helloworld

helloworld.cpp

#include <eosiolib/eosio.hpp>
#include <eosiolib/print.hpp>

using namespace eosio; 
class hello : public contract {
    public: using contract::contract;
    [[eosio::action]] void hi( name user ) {
        require_auth( user );
        print( "Hello, ", user);
    }
};
EOSIO_DISPATCH( hello, (hi))