71 lines
3.0 KiB
Solidity
71 lines
3.0 KiB
Solidity
// Abstract contract for the full ERC 20 Token standard
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// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
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pragma solidity ^0.4.21;
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contract EIP20 {
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event Transfer(address indexed _from, address indexed _to, uint256 _value);
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event Approval(address indexed _owner, address indexed _spender, uint256 _value);
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uint256 public totalSupply;
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uint256 constant private MAX_UINT256 = 2**256 - 1;
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mapping (address => uint256) public balances;
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mapping (address => mapping (address => uint256)) public allowed;
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/*
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NOTE:
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The following variables are OPTIONAL vanities. One does not have to include them.
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They allow one to customise the token contract & in no way influences the core functionality.
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Some wallets/interfaces might not even bother to look at this information.
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*/
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string public name; //fancy name: eg Simon Bucks
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uint8 public decimals; //How many decimals to show.
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string public symbol; //An identifier: eg SBX
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constructor (
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uint256 _initialAmount,
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string _tokenName,
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uint8 _decimalUnits,
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string _tokenSymbol
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) public {
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balances[msg.sender] = _initialAmount; // Give the creator all initial tokens
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totalSupply = _initialAmount; // Update total supply
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name = _tokenName; // Set the name for display purposes
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decimals = _decimalUnits; // Amount of decimals for display purposes
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symbol = _tokenSymbol; // Set the symbol for display purposes
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}
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function transfer(address _to, uint256 _value) public returns (bool success) {
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require(balances[msg.sender] >= _value);
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balances[msg.sender] -= _value;
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balances[_to] += _value;
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emit Transfer(msg.sender, _to, _value); //solhint-disable-line indent, no-unused-vars
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return true;
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}
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function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
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uint256 allowance = allowed[_from][msg.sender];
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require(balances[_from] >= _value && allowance >= _value);
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balances[_to] += _value;
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balances[_from] -= _value;
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if (allowance < MAX_UINT256) {
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allowed[_from][msg.sender] -= _value;
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}
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emit Transfer(_from, _to, _value); //solhint-disable-line indent, no-unused-vars
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return true;
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}
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function balanceOf(address _owner) public view returns (uint256 balance) {
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return balances[_owner];
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}
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function approve(address _spender, uint256 _value) public returns (bool success) {
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allowed[msg.sender][_spender] = _value;
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emit Approval(msg.sender, _spender, _value); //solhint-disable-line indent, no-unused-vars
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return true;
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}
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function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
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return allowed[_owner][_spender];
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}
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}
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