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pragma solidity >0.4.21;
import "./Token.sol";
contract StandardToken is Token {
uint256 supply;
mapping (address => uint256) balance;
mapping (address =>
mapping (address => uint256)) m_allowance;
constructor(address _initialOwner, uint256 _supply) public {
supply = _supply;
balance[_initialOwner] = _supply;
}
function balanceOf(address _account) constant public returns (uint) {
return balance[_account];
}
function totalSupply() constant public returns (uint) {
return supply;
}
function transfer(address _to, uint256 _value) public returns (bool success) {
return doTransfer(msg.sender, _to, _value);
}
function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
if (m_allowance[_from][msg.sender] >= _value) {
if (doTransfer(_from, _to, _value)) {
m_allowance[_from][msg.sender] -= _value;
}
return true;
} else {
return false;
}
}
function doTransfer(address _from, address _to, uint _value) internal returns (bool success) {
if (balance[_from] >= _value && balance[_to] + _value >= balance[_to]) {
balance[_from] -= _value;
balance[_to] += _value;
emit Transfer(_from, _to, _value);
return true;
} else {
return false;
}
}
function approve(address _spender, uint256 _value) public returns (bool success) {
m_allowance[msg.sender][_spender] = _value;
emit Approval(msg.sender, _spender, _value);
return true;
}
function allowance(address _owner, address _spender) constant public returns (uint256) {
return m_allowance[_owner][_spender];
}
}
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