學習Solidity之Hello world

npm install -g truffle ganache-cli

ganache-cli

mkdir hello
cd hello
truffle init
truffle create contract HelloWorld #建立合約

// SPDX-License-Identifier: MIT
pragma solidity >=0.4.22 <0.9.0;

contract HelloWorld {
  // constructor() public {
  // }

  function sayHello() public pure returns (string memory){
    return ("Hello World");
  }
}

truffle compile

var HelloWorld = artifacts.require("HelloWorld");
module.exports = function(deployer) {
　　deployer.deploy(HelloWorld);
};

truffle migrate

truffle console

> let contract
> HelloWorld.deployed().then(instance => contract = instance)
> contract.sayHello.call()

// SPDX-License-Identifier: MIT
pragma solidity >=0.4.22 <0.9.0;

contract MyName {
  string public _name;

  constructor() {
    _name="Please Type Your Name";
  }

  function setName(string memory name) public{
    _name = name ;
  }

  function getName() public view returns (string memory){
    return _name;
  }
}

truffle console
let contract
MyName.deployed().then(instance => contract = instance)

contract.getName.call()
contract.setName("Test Name")

contract.getName.call()