ERC-20 Standard

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IERC20Metadata

IERC20Metadata.solInterface for IERC20Metadata Fungible Tokens

1interface IERC20Metadata is IERC20 { {
2	function name() external view returns (string memory);
3	function symbol() external view returns (string memory);
4	function decimals() external view returns (uint8);
5}

IERC-20

IERC-20.solInterface for ERC-20 Fungible Tokens

1interface IERC20 {
2	event Transfer(address indexed from, address indexed to, uint256 value);
3	event Approval(address indexed owner, address indexed spender, uint256 value);
4	function totalSupply() external view returns (uint256);
5	function balanceOf(address account) external view returns (uint256);
6	function transfer(address to, uint256 value) external returns (bool);
7	function allowance(address owner, address spender) external view returns (uint256);
8	function approve(address spender, uint256 value) external returns (bool);
9	function transferFrom(address from, address to, uint256 value) external returns (bool);
10}

ERC-20 Functions

The different implementation correspond to the patterns (depending on where they have the supply)

ERC-20.solERC-20 Fungible Tokens

1interface IERC20 {
2	...
3	function name() external view returns (string memory);
4	function symbol() external view returns (string memory);
5	function decimals() external view returns (uint8);
6	function totalSupply() external view returns (uint256);
7	function balanceOf(address account) external view returns (uint256);
8	function transfer(address to, uint256 value) external returns (bool);
9	function allowance(address owner, address spender) external view returns (uint256);
10	function approve(address spender, uint256 value) external returns (bool);
11	function transferFrom(address from, address to, uint256 value) external returns (bool);
12	event Transfer(address indexed from, address indexed to, uint256 value);
13	event Approval(address indexed owner, address indexed spender, uint256 value);
14}

ERC-20 Storage

ERC-20.solERC-20 Fungible Tokens

1interface IERC20 {
2	string private _name;
3	string private _symbol;
4	uint256 private _totalSupply;
5	mapping(address account => uint256) private _balances;
6	mapping(address account => mapping(address spender => uint256)) private _allowances;
7	...
8}