智能合約開發實戰(18) - Interface

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;
//建一個contract，需先佈署到區塊鏈上面，後面interface才能調用
contract Counter {
　　uint public count;
　　function increment() external {
　　　　count ++;//每次調用就+1
　　}
}
//實現function接口
interface ICounter {
　　function increment() external; 
}
contract MyContract {
　　//從接口去調用另外一個smart contract
　　function incrementCounter(address _counter) external {
　　　　ICounter(_counter).increment();
　　}
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;
//Uniswap example
interface UniswapV2Factory {
　　function getPair(address tokenA, address tokenB) external view returns(address pair);
}
interface UniswapV2Pair {
　　function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLost);
}
contract UniswapExample {
　　address private factory = 0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f;
　　address private dai = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
　　address private weth = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
　　function getTokenReserves() external view returns (uint, uint) {
　　　　address pair = UniswapV2Factory(factory).getPair(dai, weth);
　　　　(uint reserve0, uint reserve1, ) = UniswapV2Pair(pair).getReserves();
　　　　return (reserve0, reserve1);
　　}
}