Cannot access variables in contract

Question

This is my contract-

pragma solidity ^0.4.0;
contract helloworld { 
     uint public balance;
    function helloworld(){
        balance = 1000;
    }

    function getBalance()  returns(uint) {
        return balance; 
    } 
}

I ran truffle compile and truffle migrate. Then I'm trying to access the balance variable by

helloworld.deployed().balance.call();

I'm getting the following error-

TypeError: Cannot read property 'call' of undefined
    at evalmachine.<anonymous>:1:30
    at ContextifyScript.Script.runInContext (vm.js:35:29)
    at Object.runInContext (vm.js:89:6)
    at TruffleInterpreter.interpret (C:\Users\ujjwa\AppData\Roaming\npm\node_modules\truffle\lib\repl.js:136:17)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)
    at REPLServer.<anonymous> (repl.js:538:10)
    at emitOne (events.js:96:13)
    at REPLServer.emit (events.js:188:7)
    at REPLServer.Interface._onLine (readline.js:230:10)

Answer 1

if you use truffle V3.x (truffle version) try

helloworld.deployed().then(function(instance){helloworld=instance})

then

helloworld.balance.call()