【许晓笛】49行代码就能发币？而且EOS连例子都给你了

   private:
//account 结构体 
struct account {
//EOS 账户名
         account_name owner;
//余额
uint64_t     balance;
//主键
uint64_t primary_key()const { return owner; }

      eosio::multi_index<N(accounts), account> _accounts;

      void add_balance( account_name payer, account_name to, uint64_t q ) {
//在列表中查询，看要收币的用户是否已经在列表中。
auto toitr = _accounts.find( to );
//如果不在列表中，说明用户从未持有过这种币，要将用户加入列表
if( toitr == _accounts.end() ) {
//增加一个用户
           _accounts.emplace( payer, [&]( auto& a ) {
              a.owner = to;
//因为之前没有这种币，用户名下的余额为要接收的数量
              a.balance = q;
           });
//如果用户在列表中，说明已经持有或持有过这种币
         } else {
           _accounts.modify( toitr, 0, [&]( auto& a ) {
//直接将余额增加要转入的数量
              a.balance += q;
//判断用户余额是否溢出（余额增加了q，之后数量应该大于q）
              eosio_assert( a.balance >= q, "overflow detected" );
           });
         }
      }

  public:
      simpletoken( account_name self )
      :contract(self),_accounts( _self, _self){}

      void transfer( account_name from, account_name to, uint64_t quantity ) {
//从付款方获取权限
         require_auth( from );
//从列表中搜索发币方账户
const auto& fromacnt = _accounts.get( from );
//验证付款方余额，是否透支
         eosio_assert( fromacnt.balance >= quantity, "overdrawn balance" );
//从付款方减去代币
         _accounts.modify( fromacnt, from, [&]( auto& a ){ a.balance -= quantity; } );
//收款方增加代币（之前实现的私有函数）
         add_balance( from, to, quantity );
      }

      void issue( account_name to, uint64_t quantity ) {
//得到合约主人的权限
         require_auth( _self );
//直接印钱
         add_balance( _self, to, quantity );

EOSIO_ABI( simpletoken, (transfer)(issue) )

#define EOSIO_ABI( TYPE, MEMBERS ) \
extern "C" { \
   void apply( uint64_t receiver, uint64_t code, uint64_t action ) { \
      auto self = receiver; \
if( code == self ) { \
         TYPE thiscontract( self ); \
         switch( action ) { \
            EOSIO_API( TYPE, MEMBERS ) \
         } \
         eosio_exit(0); \
      } \
   } \
} \

#include <eosiolib/eosio.hpp>

class simpletoken : public eosio::contract {
public:
      simpletoken( account_name self )
      :contract(self),_accounts( _self, _self){}

void transfer( account_name from, account_name to, uint64_t quantity ) {
         require_auth( from );

const auto& fromacnt = _accounts.get( from );
         eosio_assert( fromacnt.balance >= quantity, "overdrawn balance" );
         _accounts.modify( fromacnt, from, [&]( auto& a ){ a.balance -= quantity; } );

         add_balance( from, to, quantity );
      }

void issue( account_name to, uint64_t quantity ) {
         require_auth( _self );
         add_balance( _self, to, quantity );
      }

private:
struct account {
         account_name owner;
uint64_t     balance;

uint64_t primary_key()const { return owner; }
      };

      eosio::multi_index<N(accounts), account> _accounts;

void add_balance( account_name payer, account_name to, uint64_t q ) {
auto toitr = _accounts.find( to );
if( toitr == _accounts.end() ) {
           _accounts.emplace( payer, [&]( auto& a ) {
              a.owner = to;
              a.balance = q;
           });
         } else {
           _accounts.modify( toitr, 0, [&]( auto& a ) {
              a.balance += q;
              eosio_assert( a.balance >= q, "overflow detected" );
           });
         }
      }
};

EOSIO_ABI( simpletoken, (transfer)(issue) )