CH3 Ethereum Programming Basics

Smart Contracts can be written in

• Java, C++, Solidity and JavaScript, because the Ethereum Blockchain is completely

  language agnostic and cross compilers for every major language exist.

• Solidity, Viper, LLL and Serpent, because those are high level languages that are compiled down to bytecode

• Solidity and JavaScript, because those are the official first implementations for Distributed

  applications and the Blockchain fully supports those languages

Solidity gets compiled to

• Bytecode that can’t be understood by humans

• Bytecodes which are essentially opcodes running instruction by instruction

Gas is used

• Depending on the instruction/opcode run by the Ethereum Blockchain

• Is a fixed amount for the length of your smart contract

To store almost all data in the Ethereum Blockchain

• ALinked List with pointers to previous blocks hashes is used

• A Merkle Patricia Tree is used

• A Radix Tree is used because the Merkle Patricia Tree is too inefficient

You interact with a smart contract and see a gas usage of 50,000 gas with a gas cost of

15Gwei, how much Ether would you have to pay to the miner?

• 750,000,000,000,000 Wei

• 750,000,000,000 Wei

• 750,000,000 Wei

• A flat fee of 1 Ether

Checking the balance of an address inside a loop of a smart contract constantly

• Doesn't cost any gas

• Cost gas every time we check the balance

Gas costs accrue on

• Sending a transaction no matter the content

• Sending a transaction only with a new smart contract deployment

• Sending a transaction only interacting with an already deployed smart contract

EVM assembly

• Is much better than Solidity and a viable alternative

• Is what every highevel language gets compiled to

• Is another language similar to LLL, more secure than Solidity.

Smart Contracts

• Are always living on the same address, because the blockchain is deterministic. So,

  one account can always have one smart contract

• Are having the same address as the EOA

• Are sitting on their own address. The Address is created from the nonce and the EOA

  address and could be known in advance before deploying the smart contract.

• The address of the smart contract is a random address which gets generated by the

  miner who mines the contract-creation transaction.