◆ Purpose

to create the pair address of tokenA and tokenB

◆ Input & Return value

(address tokenA, address tokenB) ⇒ (address pair)

◆ Example

tokenA(USDC) = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48

tokenB(WETH) = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2

⇒

pair(USDC/WETH) = 0xB4e16d0168e52d35CaCD2c6185b44281Ec28C9Dc

◆ Code and Explain

create2 is one of opcode to create new contract address.

There are two opcodes to create contract address. “CREATE” and “CREATE2”.

If you want to dive deep to this, check this page 👉 Create2 

function createPair(address tokenA, address tokenB) external returns (address pair) {
        require(tokenA != tokenB, 'UniswapV2: IDENTICAL_ADDRESSES');
        (address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2: ZERO_ADDRESS');
        require(getPair[token0][token1] == address(0), 'UniswapV2: PAIR_EXISTS'); // single check is sufficient
        bytes memory bytecode = type(UniswapV2Pair).creationCode;
        bytes32 salt = keccak256(abi.encodePacked(token0, token1));
        assembly {
            pair := create2(0, add(bytecode, 32), mload(bytecode), salt)
        }
        IUniswapV2Pair(pair).initialize(token0, token1);
        getPair[token0][token1] = pair;
        getPair[token1][token0] = pair; // populate mapping in the reverse direction
        allPairs.push(pair);
        emit PairCreated(token0, token1, pair, allPairs.length);
    }

◆ Resources

https://github.com/Uniswap/v2-core/blob/master/contracts/UniswapV2Factory.sol#L23

Create2