Part 3 - Hello World of EOS DAWN-V3.0.0 Smart Contract Development

Author: Li Yuechun | Founder of Confucius Institute
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Li Yuechun Blockchain Blog: http://liyuechun.org

Whether it is C、C++、Javaor any other language, when we first start learning, we will start from the HelloWorldbeginning. This article mainly explains EOS DAWN-V3.0.0the development of smart contracts Hello World.

Before reading this article, please read the following two introductory articles.

• Part 1 - Teach you to sort out the ins and outs of building various EOS development environments
• Part 2 - EOS Currency Contract Case

1. Write contract code

Create a folder on the desktop, such as: 0418, Atomopen the 0418folder with. Create a new file Hello.cppfile and copy the following source code into the Hello.cppfile.

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

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//用eosio命名空间
using namespace eosio;

//所有的智能合约都继承自contract类
class Hello : public eosio::contract {

  public:
      using contract::contract;

      /// @abi action
      void hi( account_name user ) {
         print( "Hello, ", name{user} );
      }

};
EOSIO_ABI( Hello, (hi) )

2. Generate .wastfiles

liyuechun:Project yuechunli$ eosiocpp -o Hello.wast Hello.cpp
liyuechun:Project yuechunli$ ls
Hello.cpp   Hello.wast
liyuechun:Project yuechunli$ 

3. Generate .abifiles

liyuechun:Project yuechunli$ eosiocpp -g Hello.abi Hello.cpp 
Generated Hello.abi ...
liyuechun:Project yuechunli$ ls
Hello.abi   Hello.cpp   Hello.wast
liyuechun:Project yuechunli$

• Hello.abiThe contents of the file are as follows:

{
  "____comment": "This file was generated by eosio-abigen. DO NOT EDIT - 2018-04-18T08:15:50",
  "types": [],
  "structs": [{
      "name": "hi",
      "base": "",
      "fields": [{
          "name": "user",
          "type": "account_name"
        }
      ]
    }
  ],
  "actions": [{
      "name": "hi",
      "type": "hi",
      "ricardian_contract": ""
    }
  ],
  "tables": [],
  "clauses": []
}

4. Create a wallet account

4.1 Create wallet

liyuechun:Hello yuechunli$ cleos wallet create
Creating wallet: default
Save password to use in the future to unlock this wallet.
Without password imported keys will not be retrievable.
"PW5J3rx7Bfg9zb8Kf2owTytccFyJqtDTrqnUX8iBRRUvbwM8RyzRL"

PW5J3rx7Bfg9zb8Kf2owTytccFyJqtDTrqnUX8iBRRUvbwM8RyzRLIt must be saved, and this password is required to unlock the wallet.

4.2 Create two sets of keys

liyuechun:Hello yuechunli$ ./cleos create key
-bash: ./cleos: No such file or directory
liyuechun:Hello yuechunli$ cleos create key
Private key: 5K7QdknUZsF9apdBhD8TDMZGJjw8zJ8esYwS173YyFRv2453Z9t
Public key: EOS5RU8VsYBLnN5snGeUKmt1sDDzpvQbGyW7LPP6qEryaFctYieCK
liyuechun:Hello yuechunli$ cleos create key
Private key: 5J8kComGiQHZyNmH6VvkHgtFggeQemazLpihKR4QW75DNkWTVdA
Public key: EOS5fqiC3VFAJ1riMrKf8vzD28nqd4EpXvZGpXt6YewEBnH8DYinG

4.3 Import the private key to the wallet

liyuechun:Hello yuechunli$ cleos wallet import 5K7QdknUZsF9apdBhD8TDMZGJjw8zJ8esYwS173YyFRv2453Z9t
imported private key for: EOS5RU8VsYBLnN5snGeUKmt1sDDzpvQbGyW7LPP6qEryaFctYieCK
liyuechun:Hello yuechunli$ cleos wallet import 5J8kComGiQHZyNmH6VvkHgtFggeQemazLpihKR4QW75DNkWTVdA
imported private key for: EOS5fqiC3VFAJ1riMrKf8vzD28nqd4EpXvZGpXt6YewEBnH8DYinG

4.4 Create an account

liyuechun:cleos yuechunli$ ./cleos create account eosio liyc111 EOS5RU8VsYBLnN5snGeUKmt1sDDzpvQbGyW7LPP6qEryaFctYieCK EOS5fqiC3VFAJ1riMrKf8vzD28nqd4EpXvZGpXt6YewEBnH8DYinG

5. Deploy the contract

liyuechun:build yuechunli$ cleos set contract liyc111 ./contracts/Hello
Reading WAST/WASM from ./contracts/Hello/Hello.wast...
Assembling WASM...
Publishing contract...
executed transaction: 21d891e425f3d65852432e2b6a78146e2e2992a267c9f28c8ce56cd5dbea98f2  1632 bytes  2200576 cycles
#         eosio <= eosio::setcode               {"account":"liyc111","vmtype":0,"vmversion":0,"code":"0061736d0100000001370b60027f7e0060027e7e006001...
#         eosio <= eosio::setabi                {"account":"liyc111","abi":{"types":[],"structs":[{"name":"hi","base":"","fields":[{"name":"user","t...
liyuechun:build yuechunli$ cleos get code liyc111
code hash: e387951f9a18870f2c151fbceea5b279a3861bdabab58ea87a67296a8a6583d0
liyuechun:build yuechunli$ 

6. Execute the contract

6.1 Unlock the wallet

PW5J3rx7Bfg9zb8Kf2owTytccFyJqtDTrqnUX8iBRRUvbwM8RyzRLis the password to create the wallet yes.

liyuechun:build yuechunli$ cleos wallet unlock --password PW5J3rx7Bfg9zb8Kf2owTytccFyJqtDTrqnUX8iBRRUvbwM8RyzRL
Unlocked: default

6.2 Execute the contract

liyuechun:build yuechunli$ cleos push action liyc111 hi '{"user":"liyc1215"}' -p liyc111
executed transaction: 9abcaec2711ce31c693e5124af507f34aa666702bd5bb230ec31ddd6903248a8  232 bytes  102400 cycles
#       liyc111 <= liyc111::hi                  {"user":"liyc1215"}
>> Hello, liyc1215
liyuechun:build yuechunli$ 

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