Solidity by Example
version 0.7.6

Precompute Contract Address with Create2

Contract address can be precomputed, before the contract is deployed, using create2

// SPDX-License-Identifier: MIT
pragma solidity ^0.7.6;

contract Factory {
    event Deployed(address addr, uint256 salt);

    // 1. Get bytecode of contract to be deployed
    // NOTE: _owner and _foo are arguments of the TestContract's constructor
    function getBytecode(address _owner, uint _foo) public pure returns (bytes memory) {
        bytes memory bytecode = type(TestContract).creationCode;

        return abi.encodePacked(bytecode, abi.encode(_owner, _foo));

    // 2. Compute the address of the contract to be deployed
    // NOTE: _salt is a random number used to create an address
    function getAddress(bytes memory bytecode, uint _salt) public view returns (address) {
        bytes32 hash = keccak256(

        // NOTE: cast last 20 bytes of hash to address
        return address(uint160(uint256(hash)));

    // 3. Deploy the contract
    // NOTE:
    // Check the event log Deployed which contains the address of the deployed TestContract.
    // The address in the log should equal the address computed from above.
    function deploy(bytes memory bytecode, uint _salt) public payable {
        address addr;

        NOTE: How to call create2

        create2(v, p, n, s)
        create new contract with code at memory p to p + n
        and send v wei
        and return the new address
        where new address = first 20 bytes of keccak256(0xff + address(this) + s + keccak256(mem[pā€¦(p+n)))
              s = big-endian 256-bit value
        assembly {
            addr := create2(
                callvalue(), // wei sent with current call
                // Actual code starts after skipping the first 32 bytes
                add(bytecode, 0x20),
                mload(bytecode), // Load the size of code contained in the first 32 bytes
                _salt // Salt from function arguments

            if iszero(extcodesize(addr)) {
                revert(0, 0)

        emit Deployed(addr, _salt);

contract TestContract {
    address public owner;
    uint public foo;

    constructor(address _owner, uint _foo) payable {
        owner = _owner;
        foo = _foo;

    function getBalance() public view returns (uint) {
        return address(this).balance;

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