Module 4 Adding functionality

Smart contracts can have functions that can perform tasks based on user calls on the blockchain. Edit the HelloWorld smart contract as follows:-

pragma solidity ^0.4.22;


contract HelloWorld {
  string helloMsg;
  constructor() {
    helloMsg = "Hello World!!!";
  }

  function getHelloMsg() returns (string){
    return helloMsg;
  }

  function setHelloMsg(string _helloMsg) returns (bool success){
    helloMsg = _helloMsg;
    return true;
  }
}

On terminal run the following command to compile the smart contract:-

truffle compile

Once it is compiled, migrate the new smart contract to the blockchain:-

truffle migrate --network usc --reset

Connect to truffle console:-

truffle console --network usc

To call getHelloMsg function, type the following command on truffle console:-

HelloWorld.deployed().then(function(d){return d.getHelloMsg.call();});

To set new message call setHelloMsg function:-

HelloWorld.deployed().then(function(d){return d.setHelloMsg("Hello!!!");});

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