pragma solidity ^0.4.11;

contract HelloWorldContract {
    string word = "Hello World";
    address issuer;

    //constructor
    function HelloWorldContract() {
        issuer = msg.sender;
    }

    //modifier is like function, it will call before executing function.
    modifier ifIssuer() {
        //msg.sender is the
        if(issuer != msg.sender) {
            throw;  //Throw exception error
        }
        else {
            _;  //continue
        }
    }
    //getter function, only thing to note down is 'constant'
    function getWord() constant returns (string) {
        return word;
    }
    //setter function with 'ifIssuer' as modifier
    function setWord(string newWord) ifIssuer returns (string) {
        word = newWord;
        return  "This is the creator";
    }

}