342-ERC20代币

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ERC20






 contract ERC20 {
    function totalSupply() constant returns (uint totalSupply);   
    function balanceOf(address _owner) constant returns (uint balance);
    function transfer(address _to, uint _value) returns (bool success);  
    function transferFrom(address _from, address _to, uint _value) returns (bool success);    

    function approve(address _spender, uint _value) returns (bool success);
    function allowance(address _owner, address _spender) constant returns (uint remaining);

    event Transfer(address indexed _from, address indexed _to, uint _value);
    event Approval(address indexed _owner, address indexed _spender, uint _value);

    string public constant name = "4FunCoin";
    string public constant symbol = "4FC";
    uint8 public constant decimals = 18;  
}





cntract ERC20Token{
    function totalSupply() constant returns (uint totalSupply);   
    function balanceOf(address _owner) constant returns (uint balance);
    function transfer(address _to, uint _value) returns (bool success);  
    function transferFrom(address _from, address _to, uint _value) returns (bool success);    

    function approve(address _spender, uint _value) returns (bool success);
    function allowance(address _owner, address _spender) constant returns (uint remaining);

    event Transfer(address indexed _from, address indexed _to, uint _value);
    event Approval(address indexed _owner, address indexed _spender, uint _value);

    string public constant name = "4FunCoin";
    string public constant symbol = "4FC";
    uint8 public constant decimals = 18; 
}








contract ERC20 {
牋牋牋牋function totalSupply() constant returns (uint totalSupply);牋 ???//???????
????function balanceOf(address _owner) constant returns (uint balance); //??????
 牋牋牋爁unction transfer(address _to, uint _value)returns(bool success); // ??Token?????(??)
牋牋牋牋function transferFrom(address _from, address _to, uint _value) returns (bool success); //???from ??token?to??
  牋牋牋function approve(address _spender, uint _value)returns(bool success);//??_spender???????token
牋牋牋牋function allowance(address _owner, address _spender) constant returns (uint remaining);//????spender???Token??
牋牋牋牋event Transfer(address indexed _from, address indexed _to, uint _value);//transfer??????????
牋牋牋牋event Approval(address indexed _owner, address indexed _spender, uint _value); //approve??????????
}









1.totalSupply
2.balanceOf
3.transfer
4.transferFrom
5.approve
6.allowance

7.event Transfer
8.event Approval

9.name 
10.symbol
11.decimals









ERC20?????????????
??????
???????????








BNB????

??,?2???
1.SafeMath
2.BNB is SafeMath



????
string public name;
string public symbol;
uint8 public decimals;
uint256 public totalSupply;
address public owner;



??map
mapping (address => uint256) public balanceOf;
????????,???map??
?? => 10
?? => 20

mapping (address => uint256) public freezeOf;
?????
??????,????









    function BNB(
        uint256 initialSupply,
        string tokenName,
        uint8 decimalUnits,
        string tokenSymbol
        ) {
        balanceOf[msg.sender] = initialSupply;              // Give the creator all initial tokens
        totalSupply = initialSupply;                        // Update total supply
        name = tokenName;                                   // Set the name for display purposes
        symbol = tokenSymbol;                               // Set the symbol for display purposes
        decimals = decimalUnits;                            // Amount of decimals for display purposes
		owner = msg.sender;
    }







if(msg.sender != owner) { throw; }

???????????:

if(msg.sender != owner) { revert(); }

assert(msg.sender == owner);

require(msg.sender == owner);










pragma solidity >=0.4.22 <0.6.0;

/**
 * Math operations with safety checks
 */
contract SafeMath {
  function safeMul(uint256 a, uint256 b) internal returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function safeDiv(uint256 a, uint256 b) internal returns (uint256) {
    assert(b > 0);
    uint256 c = a / b;
    assert(a == b * c + a % b);
    return c;
  }

  function safeSub(uint256 a, uint256 b) internal returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function safeAdd(uint256 a, uint256 b) internal returns (uint256) {
    uint256 c = a + b;
    assert(c>=a && c>=b);
    return c;
  }

  function assert(bool assertion) internal {
    require(assertion==true);
  }
}
contract BNB is SafeMath{
    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;
	address payable public owner;

    /* This creates an array with all balances */
    mapping (address => uint256) public balanceOf;
	mapping (address => uint256) public freezeOf;
    mapping (address => mapping (address => uint256)) public allowance;

    /* This generates a public event on the blockchain that will notify clients */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /* This notifies clients about the amount burnt */
    event Burn(address indexed from, uint256 value);
	
	/* This notifies clients about the amount frozen */
    event Freeze(address indexed from, uint256 value);
	
	/* This notifies clients about the amount unfrozen */
    event Unfreeze(address indexed from, uint256 value);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    constructor(
        uint256 initialSupply,
        string memory tokenName,
        uint8 decimalUnits,
        string memory tokenSymbol) public {
        balanceOf[msg.sender] = initialSupply;              // Give the creator all initial tokens
        totalSupply = initialSupply;                        // Update total supply
        name = tokenName;                                   // Set the name for display purposes
        symbol = tokenSymbol;                               // Set the symbol for display purposes
        decimals = decimalUnits;                            // Amount of decimals for display purposes
		owner = msg.sender;
    }
    

    /* Send coins */
    function transfer(address _to, uint256 _value) public {
        require(_to != 0x0000000000000000000000000000000000000000);         // Prevent transfer to 0x0 address. Use burn() instead
        require(_value > 0);
		require(balanceOf[msg.sender] >= _value);                           // Check if the sender has enough
        require(balanceOf[_to] + _value >= balanceOf[_to]);                 // Check for overflows       
        
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                // Subtract from the sender
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);                              // Add the same to the recipient
        emit Transfer(msg.sender, _to, _value);                                  // Notify anyone listening that this transfer took place
    }

    /* Allow another contract to spend some tokens in your behalf */
    function approve(address _spender, uint256 _value) public returns (bool success) {
		if (_value <= 0) revert();
        allowance[msg.sender][_spender] = _value;
        return true;
    }
       

    /* A contract attempts to get the coins */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        if (_to == 0x0000000000000000000000000000000000000000) revert();                                // Prevent transfer to 0x0 address. Use burn() instead
		if (_value <= 0) revert(); 
        if (balanceOf[_from] < _value) revert();                 // Check if the sender has enough
        if (balanceOf[_to] + _value < balanceOf[_to]) revert();  // Check for overflows
        if (_value > allowance[_from][msg.sender]) revert();     // Check allowance
        balanceOf[_from] = SafeMath.safeSub(balanceOf[_from], _value);                           // Subtract from the sender
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);                             // Add the same to the recipient
        allowance[_from][msg.sender] = SafeMath.safeSub(allowance[_from][msg.sender], _value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    function burn(uint256 _value) public returns (bool success) {
        if (balanceOf[msg.sender] < _value) revert();            // Check if the sender has enough
		if (_value <= 0) revert(); 
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                      // Subtract from the sender
        totalSupply = SafeMath.safeSub(totalSupply,_value);                                // Updates totalSupply
        emit Burn(msg.sender, _value);
        return true;
    }
	
	function freeze(uint256 _value) public returns (bool success) {
        if (balanceOf[msg.sender] < _value) revert();            // Check if the sender has enough
		if (_value <= 0) revert(); 
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                      // Subtract from the sender
        freezeOf[msg.sender] = SafeMath.safeAdd(freezeOf[msg.sender], _value);                                // Updates totalSupply
        emit Freeze(msg.sender, _value);
        return true;
    }
	
	function unfreeze(uint256 _value) public returns (bool success) {
        if (freezeOf[msg.sender] < _value) revert();            // Check if the sender has enough
		if (_value <= 0) revert(); 
        freezeOf[msg.sender] = SafeMath.safeSub(freezeOf[msg.sender], _value);                      // Subtract from the sender
		balanceOf[msg.sender] = SafeMath.safeAdd(balanceOf[msg.sender], _value);
        emit Unfreeze(msg.sender, _value);
        return true;
    }
	
	// transfer balance to owner
	function withdrawEther(uint256 amount) public {
		if(msg.sender != owner) revert();
		owner.transfer(amount);
	}
	
	// can accept ether
	function() payable external{
    }
}