pragma solidity ^ 0.4.2;

contract tokenRecipient {
    function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData);
}

contract ERC20 {
    /* Public variables of the token */
    string public standard = 'CREDITS';
    string public name = 'CREDITS';
    string public symbol = 'CS';
    uint8 public decimals = 6;
    uint256 public totalSupply = 1000000000000000;

    /* This creates an array with all balances */
    mapping(address => uint256) public balanceOf;
    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);

    /* Initializes contract with initial supply tokens to the creator of the contract */

    function ERC20() {
        balanceOf[msg.sender] = totalSupply;
    }
    /* Send coins */
    function transfer(address _to, uint256 _value) {
        if (balanceOf[msg.sender] < _value) throw; // Check if the sender has enough
        if (balanceOf[_to] + _value < balanceOf[_to]) throw; // Check for overflows
        balanceOf[msg.sender] -= _value; // Subtract from the sender
        balanceOf[_to] += _value; // Add the same to the recipient
        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)
    returns(bool success) {
        allowance[msg.sender][_spender] = _value;
        tokenRecipient spender = tokenRecipient(_spender);
        return true;
    }

    /* Approve and then comunicate the approved contract in a single tx */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData)
    returns(bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }

    /* A contract attempts to get the coins */
    function transferFrom(address _from, address _to, uint256 _value) returns(bool success) {
        if (balanceOf[_from] < _value) throw; // Check if the sender has enough
        if (balanceOf[_to] + _value < balanceOf[_to]) throw; // Check for overflows
        if (_value > allowance[_from][msg.sender]) throw; // Check allowance
        balanceOf[_from] -= _value; // Subtract from the sender
        balanceOf[_to] += _value; // Add the same to the recipient
        allowance[_from][msg.sender] -= _value;
        Transfer(_from, _to, _value);
        return true;
    }

    /* This unnamed function is called whenever someone tries to send ether to it */
    function () {
        throw; // Prevents accidental sending of ether
    }
}