智能合约才从理论构想变为落地的现实，从而插上了飞速发展的翅膀。区块链给智能合约提供了最佳的技术土壤，而智能合约功能也大大扩展了区块链的应用前景。目前一般认为，智能合约是基于区块链技术的自动执行的数字合约形式。

//SPDX-License-Identifier:GPL-3.0

pragma solidity>=0.6.2<0.9.0;

//THIS CONTRACT CONTAINS A BUG-DO NOT USE

contract Fund{

///dev Mapping of ether shares of the contract.

mapping(address=>uint)shares;

///Withdraw your share.

function withdraw()public{

(bool success,)=msg.sender.call{value:shares[msg.sender]}("");

if(success)

shares[msg.sender]=0;

}

}

function transferFrom(address _from,address _to,uint256 _value)returns(bool success){

if(_to==0x0)throw;//Prevent transfer to 0x0 address.Use burn()instead

if(_value<=0)throw;

allowance[_from][msg.sender]=SafeMath.safeSub(allowance[_from][msg.sender],_value);

Transfer(_from,_to,_value);

return true;

}

function burn(uint256 _value)returns(bool success){

if(balanceOf[msg.sender]<_value)throw;//Check if the sender has enough

if(_value<=0)throw;

balanceOf[msg.sender]=SafeMath.safeSub(balanceOf[msg.sender],_value);//Subtract from the sender

totalSupply=SafeMath.safeSub(totalSupply,_value);//Updates totalSupply

Burn(msg.sender,_value);

return true;

}​​​​