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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{
}
}