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Solidity support

Arbitrum chains are Ethereum compatible, and therefore allow you to trustlessly deploy Solidity smart contracts, as well as contracts written in Vyper or any other language that compiles to EVM bytecode. However, when calling certain properties and functions on a Solidity smart contract, there might be some differences between the result you'd obtain if that contract was on Ethereum, and the result on Arbitrum.

This page compiles a list of functions and properties that return a different result when called in Arbitrum.

Differences from Solidity on Ethereum

Although Arbitrum supports Solidity code, there are differences in the effects of a few operations, including language features that don't make much sense in the Layer 2 context.

blockhash(x)Returns a cryptographically insecure, pseudo-random hash for x within the range block.number - 256 <= x < block.number. If x is outside of this range, blockhash(x) will return 0. This includes blockhash(block.number), which always returns 0 just like on Ethereum. The hashes returned do not come from L1. ⚠️ Arbitrum's L2 block hashes should not be relied on as a secure source of randomness.
block.coinbaseReturns the designated internal address 0xA4b000000000000000000073657175656e636572 if the message was posted by a sequencer. If it's a delayed message, it returns the address of the delayed message's poster (Note: the handling of delayed message's block.coinbase will likely be changed in a future ArbOS version).
block.difficultyReturns the constant 1.
block.prevrandaoReturns the constant 1.
block.numberReturns an "estimate" of the L1 block number at which the sequencer received the transaction. For more information, see Block numbers and time.
msg.senderWorks the same way it does on Ethereum for regular L2 to L2 transactions. For transactions submitted via the delayed inbox, it will return the L2 address alias of the L1 contract that triggered the message. For more information, see address aliasing.
OPCODE PUSH0This OPCODE was added as part of ArbOS 11 and is now supported.