# Compute Pair Address

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)	`579e9bdec156a1150f17cf9884a4421f309e7e9be6b26dcfbd9a52883418ee21`
token0	must be strictly less than token1 by sort order.

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

# Examples

# Solidity

address factory = 0x7de800467aFcE442019884f51A4A1B9143a34fAc;
address token0 = 0xCAFE000000000000000000000000000000000000; // change me!
address token1 = 0xF00D000000000000000000000000000000000000; // change me!

address pair = address(uint(keccak256(abi.encodePacked(
  hex'ff',
  factory,
  keccak256(abi.encodePacked(token0, token1)),
  hex'579e9bdec156a1150f17cf9884a4421f309e7e9be6b26dcfbd9a52883418ee21'
))));

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