erc20-approve.sol

contract MyERCToken {
  // Create a table so that we can map
  // the addresses of contract owners to
  // those who are allowed to utilize the owner's contract
  mapping(address => mapping (address => uint256)) allowed;
  
  function approve(address _spender, uint256 _amount) returns (bool success) {
    allowed[msg.sender][_spender] = _amount;
    // Fire the event "Approval" to execute any logic
    // that was listening to it
    Approval(msg.sender, _spender, _amount);
    return true;
  }
}