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First ERC20 compliant token creation for learning purposes
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pragma solidity ^0.4.0; | |
interface ERC20 { | |
function totalSupply() public constant returns (uint _totalSupply); | |
function balanceOf(address _owner) public constant returns (uint balance); | |
function transfer(address _to, uint _value) public returns (bool success); | |
function transferFrom(address _from , address _to, uint _value) public returns (bool success); | |
function approve(address _spender, uint _value) public returns (bool success); | |
function allowance(address _owner, address _spender) public constant returns (uint remaining); | |
event Transfer(address indexed _from, address indexed _to, uint _value); | |
event Approval(address indexed _owner, address indexed _spender, uint _value); | |
} | |
contract MyFirstToken is ERC20 | |
{ | |
string public symbol; | |
string public name; | |
uint8 public decimals = 18; | |
uint256 public __totalSupply; | |
mapping (address => uint) private __balanceOf; | |
mapping (address => mapping (address => uint)) private __allowances; | |
//this is just to get the address of owner for testing purpose.. | |
//function getAddress() public returns (address) | |
//{ | |
// return msg.sender; | |
//} | |
function MyFirstToken(uint256 initialSupply, string tokenName, string tokenSymbol, uint8 decimalUnits) public | |
{ | |
__totalSupply = initialSupply; | |
__balanceOf[msg.sender] = initialSupply; | |
name = tokenName; | |
symbol = tokenSymbol; | |
decimals = decimalUnits; | |
} | |
function totalSupply() public constant returns (uint _totalSupply) | |
{ | |
_totalSupply = __totalSupply; | |
} | |
function balanceOf(address _owner) public constant returns (uint balance) | |
{ | |
balance = __balanceOf[_owner]; | |
return balance; | |
} | |
function transfer(address _to, uint _value) public returns (bool success) | |
{ | |
//first check if self has balance to transfer | |
if ( (_value > 0) && (_value <= balanceOf(msg.sender)) ) | |
{ | |
__balanceOf[msg.sender] -= _value; | |
__balanceOf[_to] += _value; | |
Transfer(msg.sender, _to, _value); | |
return true; | |
} | |
return false; | |
} | |
//Remember, to call this from an external account, have some ETHERS in them. Else nothing happens | |
function transferFrom(address _from , address _to, uint _value) public returns (bool success) | |
{ | |
if (__allowances[_from][msg.sender] > 0 && | |
_value > 0 && | |
__allowances[_from][msg.sender] >= _value) | |
{ | |
__balanceOf[_from] -= _value; | |
__balanceOf[_to] += _value; | |
__allowances[_from][msg.sender] -= _value; | |
Transfer(_from, _to, _value); | |
return true; | |
} | |
return false; | |
} | |
function approve(address _spender, uint _value) public returns (bool success) | |
{ | |
__allowances[msg.sender][_spender] = _value; | |
Approval(msg.sender, _spender, _value); | |
return true; | |
} | |
function allowance(address _owner, address _spender) public constant returns (uint remaining) | |
{ | |
return __allowances[_owner][_spender]; | |
} | |
} |
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