pragma solidity ^0.4.4; contract Token { /// @return total amount of tokens function totalSupply() constant returns (uint256 supply) {} /// @param _owner The address from which the balance will be retrieved /// @return The balance function balanceOf(address _owner) constant returns (uint256 balance) {} /// @notice send `_value` token to `_to` from `msg.sender` /// @param _to The address of the recipient /// @param _value The amount of token to be transferred /// @return Whether the transfer was successful or not function transfer(address _to, uint256 _value) returns (bool success) {} /// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from` /// @param _from The address of the sender /// @param _to The address of the recipient /// @param _value The amount of token to be transferred /// @return Whether the transfer was successful or not function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {} /// @notice `msg.sender` approves `_addr` to spend `_value` tokens /// @param _spender The address of the account able to transfer the tokens /// @param _value The amount of wei to be approved for transfer /// @return Whether the approval was successful or not function approve(address _spender, uint256 _value) returns (bool success) {} /// @param _owner The address of the account owning tokens /// @param _spender The address of the account able to transfer the tokens /// @return Amount of remaining tokens allowed to spent function allowance(address _owner, address _spender) constant returns (uint256 remaining) {} event Transfer(address indexed _from, address indexed _to, uint256 _value); event Approval(address indexed _owner, address indexed _spender, uint256 _value); } contract StandardToken is Token { function transfer(address _to, uint256 _value) returns (bool success) { //Default assumes totalSupply can't be over max (2^256 - 1). //If your token leaves out totalSupply and can issue more tokens as time goes on, you need to check if it doesn't wrap. //Replace the if with this one instead. //if (balances[msg.sender] >= _value && balances[_to] + _value > balances[_to]) { if (balances[msg.sender] >= _value && _value > 0) { balances[msg.sender] -= _value; balances[_to] += _value; Transfer(msg.sender, _to, _value); return true; } else { return false; } } function transferFrom(address _from, address _to, uint256 _value) returns (bool success) { //same as above. Replace this line with the following if you want to protect against wrapping uints. //if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && balances[_to] + _value > balances[_to]) { if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0) { balances[_to] += _value; balances[_from] -= _value; allowed[_from][msg.sender] -= _value; Transfer(_from, _to, _value); return true; } else { return false; } } function balanceOf(address _owner) constant returns (uint256 balance) { return balances[_owner]; } function approve(address _spender, uint256 _value) returns (bool success) { allowed[msg.sender][_spender] = _value; Approval(msg.sender, _spender, _value); return true; } function allowance(address _owner, address _spender) constant returns (uint256 remaining) { return allowed[_owner][_spender]; } mapping (address => uint256) balances; mapping (address => mapping (address => uint256)) allowed; uint256 public totalSupply; } //name this contract whatever you'd like contract ERC20Token is StandardToken { function () { //if ether is sent to this address, send it back. throw; } /* Public variables of the token */ /* NOTE: The following variables are OPTIONAL vanities. One does not have to include them. They allow one to customise the token contract & in no way influences the core functionality. Some wallets/interfaces might not even bother to look at this information. */ string public name; //fancy name: eg Simon Bucks uint8 public decimals; //How many decimals to show. ie. There could 1000 base units with 3 decimals. Meaning 0.980 SBX = 980 base units. It's like comparing 1 wei to 1 ether. string public symbol; //An identifier: eg SBX string public version = 'H1.0'; //human 0.1 standard. Just an arbitrary versioning scheme. // // CHANGE THESE VALUES FOR YOUR TOKEN // //make sure this function name matches the contract name above. So if you're token is called TutorialToken, make sure the //contract name above is also TutorialToken instead of ERC20Token function ERC20Token( ) { balances[msg.sender] = 1000; // Give the creator all initial tokens (100000 for example) totalSupply = 1000; // Update total supply (100000 for example) name = "Trezor01"; // Set the name for display purposes decimals = 0; // Amount of decimals for display purposes symbol = "T01"; // Set the symbol for display purposes } /* Approves and then calls the receiving contract */ function approveAndCall(address _spender, uint256 _value, bytes _extraData) returns (bool success) { allowed[msg.sender][_spender] = _value; Approval(msg.sender, _spender, _value); //call the receiveApproval function on the contract you want to be notified. This crafts the function signature manually so one doesn't have to include a contract in here just for this. //receiveApproval(address _from, uint256 _value, address _tokenContract, bytes _extraData) //it is assumed that when does this that the call *should* succeed, otherwise one would use vanilla approve instead. if(!_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _value, this, _extraData)) { throw; } return true; } }