Pack parameters example

test.cpp

#include <eosio/eosio.hpp>
#include <eosio/asset.hpp>

using namespace eosio;
using namespace std;

class test: public contract {
public:
   using contract::contract;

   /**
    * pack parameters
    */
   [[eosio::action]]
   void usepack(name from, name to, asset quantity, string memo) {
      vector<char> packed = eosio::pack(std::make_tuple(from, to, quantity, memo));
      printhex(packed.data(), packed.size());
   }


   [[eosio::action]]
   void usestream(name from, name to, asset quantity, string memo) {
      char buf[512];
      datastream<char*> ds(buf, sizeof(buf));
      ds << from;
      ds << to;
      ds << quantity;
      ds << memo;
      vector<char> packed = {buf, buf + ds.tellp()};
      printhex(packed.data(), packed.size());
   }

   /**
    * unpack parameters
    */
   struct transfer {
      name from;
      name to;
      asset quantity;
      string memo;
   };

   [[eosio::action]]
   void useunpack(vector<char> packed) {
      auto unpacked = eosio::unpack<transfer>(packed);
      print(unpacked.from, unpacked.to, unpacked.quantity, unpacked.memo);
   }


   [[eosio::action]]
   void usestream2(vector<char> packed) {
      name from;
      name to;
      asset quantity;
      string memo;

      datastream<char*> ds(packed.data(), packed.size());
      ds >> from;
      ds >> to;
      ds >> quantity;
      ds >> memo;
      print(from, to, quantity, memo);
   }
};

Thank you!