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。系统开发180-3831-9724

 //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;

 }​​​​