How to write my first Solidity "Hello World" smart contract?

Question

I have never written a smart contract before because there is a lot attached to it getting it working. But I finally want to learn it now.

I want to write a simple mininmal working smart contract which prints out something or does something similar to saying "Hello World". Is that possible?

How would such a contract look like? How to deploy it, what tools do I need?

Answer 1

The Greeter tutorial covers a basic Hello World contract. https://ethereum.org/greeter

As a quick summary, I just tested the following steps on Ubuntu 14.04. The install-geth script should also detect and work on other environments.

Note: I had to run the installation script in the first step below twice as it failed the first time.

• Install geth: bash <(curl -L https://install-geth.ethereum.org)
• Launch geth in developer mode so that we do not need to fetch the entire blockchain and can mine our own test-ether: geth --dev console
• Create a test account from geth console : personal.newAccount()
• Check your account balance (should be 0): eth.getBalance(eth.accounts[0])
• Start the miner and let it run: miner.start()
• Attach to geth via a second terminal session: geth attach
• Check that your account balance has increased: eth.getBalance(eth.accounts[0])
• Go to the online solidity compiler/editor at https://chriseth.github.io/browser-solidity/. It defaults to a Greeter contract.
• Copy and paste the greeter's Web3 deploy code to a text editor and replace /* var of type string here */ with "Hello World"
• Copy and paste the updated code to geth and wait for the Contract mined!.. message
• Test the contract with greeter.greet()
• You can destroy the contract with greeter.kill.sendTransaction({from:eth.accounts[0]})