Dapp：代表去中心化应用程序。它们是在去中心化网络或区块链上运行后端代码（主要用Solidity编写的智能合约）的应用程序。可以使用React、Vue或Angular等前端框架构建Dapp。
Web3.0是基于区块链技术实现去中心化的新型互联网，其支持新的商业和社交等模式。
Web3.0由用户和创作者主导的开放协作、隐私保护、共创共建共享的新型生态，推动发展去中心化数字经济
app定制开发还涉及到以太坊智能合约测试、以太坊智能合约安全性测试、以太坊智能合约部署测试等。 这些技术可以帮助开发者快速测试和部署dapp，从而确保dapp的可靠性和安全性。
//if fee is on,mint liquidity equivalent to 1/6th of the growth in sqrt(k)
function _mintFee(uint112 _reserve0,uint112 _reserve1)private returns(bool feeOn){
address feeTo=IUniswapV2Factory(factory).feeTo();
feeOn=feeTo!=address(0);
uint _kLast=kLast;//gas savings
if(feeOn){
if(_kLast!=0){
uint rootK=Math.sqrt(uint(_reserve0).mul(_reserve1));
uint rootKLast=Math.sqrt(_kLast);
if(rootK>rootKLast){
uint numerator=totalSupply.mul(rootK.sub(rootKLast));
uint denominator=rootK.mul(5).add(rootKLast);
uint liquidity=numerator/denominator;
if(liquidity>0)_mint(feeTo,liquidity);
}
}
}else if(_kLast!=0){
kLast=0;
}
}
//this low-level function should be called from a contract which performs important safety checks
function mint(address to)external lock returns(uint liquidity){
(uint112 _reserve0,uint112 _reserve1,)=getReserves();//gas savings
uint balance0=IERC20(token0).balanceOf(address(this));
uint balance1=IERC20(token1).balanceOf(address(this));
uint amount0=balance0.sub(_reserve0);
uint amount1=balance1.sub(_reserve1);
bool feeOn=_mintFee(_reserve0,_reserve1);
uint _totalSupply=totalSupply;//gas savings,must be defined here since totalSupply can update in _mintFee
if(_totalSupply==0){
liquidity=Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
_mint(address(0),MINIMUM_LIQUIDITY);//permanently lock the first MINIMUM_LIQUIDITY tokens
}else{
liquidity=Math.min(amount0.mul(_totalSupply)/_reserve0,amount1.mul(_totalSupply)/_reserve1);
}
require(liquidity>0,'UniswapV2:INSUFFICIENT_LIQUIDITY_MINTED');
_mint(to,liquidity);
_update(balance0,balance1,_reserve0,_reserve1);
if(feeOn)kLast=uint(reserve0).mul(reserve1);//reserve0 and reserve1 are up-to-date
emit Mint(msg.sender,amount0,amount1);
}
