Pair Addresses

getPair

The most obvious way to get the address for a pair is to call getPair on the factory. If the pair exists, this function will return its address, else address(0) (0x0000000000000000000000000000000000000000).

The “canonical” way to determine whether or not a pair exists.
Requires an on-chain lookup.

CREATE2

Thanks to some fancy footwork in the factory, we can also compute pair addresses without any on-chain lookups because of CREATE2. The following values are required for this technique:


`address`	The factory address
`salt`	`keccak256(abi.encodePacked(token0, token1))`
`keccak256(init_code)`	`0x3a1b8c90f0ece2019085f38a482fb7538bb84471f01b56464ac88dd6bece344e`

token0 must be strictly less than token1 by sort order.

Can be computed offline.
Requires the ability to perform keccak256.

Examples

Solidity

address factory = 0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f;

address pair = address(uint(keccak256(abi.encodePacked(
  hex'ff',
  factory,
  keccak256(abi.encodePacked(wusd, item)),
  hex'3a1b8c90f0ece2019085f38a482fb7538bb84471f01b56464ac88dd6bece344e'
))));