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I'm new to ethereum. I followed a tutorial and I ended up with a contract that looks like this

pragma solidity ^0.4.15; contract HelloWorld { uint public balance; function HelloWorld() { balance = 1000; } function deposit(uint _value) returns (uint _newValue) { balance += _value; return balance; } }

After the contract is deployed at testrpc I try to call the deposit function with respect to the recent changes in syntax like so:

var hw = HelloWorld.deployed(); hw.then(function(i){ return i.deposit(500) }) .then(function(r){ console.log(r) })

but I get a Error: VM Exception while processing transaction: invalid opcode How do I call this function?

Thanks.

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You should do it like this:

this.HelloWorld .deployed() .then(instance => { return instance.deposit(500,{ from: this.account }); }) .then(result => { console.log(result); }) .catch(e => { console.log(e); });
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  • Thanks Pablo! However, if I do it like that I get 'Error: invalid address'. If I replace this.account with web3.eth.accounts[0] i get 'invalid opcode' again. Commented Oct 14, 2017 at 13:58
  • Yes, sorry, I assumed you had assigned this.account to web3.eth.accounts[0]. Then, there must be a problem with the contract. Is that all the code there is to it? Commented Oct 14, 2017 at 14:04
  • That's all the code. I just discovered ether does get subtracted from the account, even though there's that error msg (opcode) Commented Oct 14, 2017 at 14:13
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    ok, it was stupid. I just restarted testrpc, recompiled and migrated the contract again, and now it works. Commented Oct 14, 2017 at 15:27

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