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fixed_supply_token.sol ERC20 Token implementation by bokkypoobah - https://theethereum.wiki/w/index.php/ERC20_Token_Standard - https://github.com/bokkypoobah
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pragma solidity ^0.4.8; | |
// ---------------------------------------------------------------------------------------------- | |
// Sample fixed supply token contract | |
// Enjoy. (c) BokkyPooBah 2017. The MIT Licence. | |
// ---------------------------------------------------------------------------------------------- | |
// ERC Token Standard #20 Interface | |
// https://github.com/ethereum/EIPs/issues/20 | |
contract ERC20Interface { | |
// Get the total token supply | |
function totalSupply() constant returns (uint256 totalSupply); | |
// Get the account balance of another account with address _owner | |
function balanceOf(address _owner) constant returns (uint256 balance); | |
// Send _value amount of tokens to address _to | |
function transfer(address _to, uint256 _value) returns (bool success); | |
// Send _value amount of tokens from address _from to address _to | |
function transferFrom(address _from, address _to, uint256 _value) returns (bool success); | |
// Allow _spender to withdraw from your account, multiple times, up to the _value amount. | |
// If this function is called again it overwrites the current allowance with _value. | |
// this function is required for some DEX functionality | |
function approve(address _spender, uint256 _value) returns (bool success); | |
// Returns the amount which _spender is still allowed to withdraw from _owner | |
function allowance(address _owner, address _spender) constant returns (uint256 remaining); | |
// Triggered when tokens are transferred. | |
event Transfer(address indexed _from, address indexed _to, uint256 _value); | |
// Triggered whenever approve(address _spender, uint256 _value) is called. | |
event Approval(address indexed _owner, address indexed _spender, uint256 _value); | |
} | |
contract FixedSupplyToken is ERC20Interface { | |
string public constant symbol = "FIXED"; | |
string public constant name = "Example Fixed Supply Token"; | |
uint8 public constant decimals = 18; | |
uint256 _totalSupply = 1000000; | |
// Owner of this contract | |
address public owner; | |
// Balances for each account | |
mapping(address => uint256) balances; | |
// Owner of account approves the transfer of an amount to another account | |
mapping(address => mapping (address => uint256)) allowed; | |
// Functions with this modifier can only be executed by the owner | |
modifier onlyOwner() { | |
if (msg.sender != owner) { | |
throw; | |
} | |
_; | |
} | |
// Constructor | |
function FixedSupplyToken() { | |
owner = msg.sender; | |
balances[owner] = _totalSupply; | |
} | |
function totalSupply() constant returns (uint256 totalSupply) { | |
totalSupply = _totalSupply; | |
} | |
// What is the balance of a particular account? | |
function balanceOf(address _owner) constant returns (uint256 balance) { | |
return balances[_owner]; | |
} | |
// Transfer the balance from owner's account to another account | |
function transfer(address _to, uint256 _amount) returns (bool success) { | |
if (balances[msg.sender] >= _amount | |
&& _amount > 0 | |
&& balances[_to] + _amount > balances[_to]) { | |
balances[msg.sender] -= _amount; | |
balances[_to] += _amount; | |
Transfer(msg.sender, _to, _amount); | |
return true; | |
} else { | |
return false; | |
} | |
} | |
// Send _value amount of tokens from address _from to address _to | |
// The transferFrom method is used for a withdraw workflow, allowing contracts to send | |
// tokens on your behalf, for example to "deposit" to a contract address and/or to charge | |
// fees in sub-currencies; the command should fail unless the _from account has | |
// deliberately authorized the sender of the message via some mechanism; we propose | |
// these standardized APIs for approval: | |
function transferFrom( | |
address _from, | |
address _to, | |
uint256 _amount | |
) returns (bool success) { | |
if (balances[_from] >= _amount | |
&& allowed[_from][msg.sender] >= _amount | |
&& _amount > 0 | |
&& balances[_to] + _amount > balances[_to]) { | |
balances[_from] -= _amount; | |
allowed[_from][msg.sender] -= _amount; | |
balances[_to] += _amount; | |
Transfer(_from, _to, _amount); | |
return true; | |
} else { | |
return false; | |
} | |
} | |
// Allow _spender to withdraw from your account, multiple times, up to the _value amount. | |
// If this function is called again it overwrites the current allowance with _value. | |
function approve(address _spender, uint256 _amount) returns (bool success) { | |
allowed[msg.sender][_spender] = _amount; | |
Approval(msg.sender, _spender, _amount); | |
return true; | |
} | |
function allowance(address _owner, address _spender) constant returns (uint256 remaining) { | |
return allowed[_owner][_spender]; | |
} | |
} |
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