ERC20Interface.sol

pragma solidity >=0.4.22 <0.7.0;

contract ERC20Interface {

    string public constant name = "Token Name";
    string public constant symbol = "SYM";
    uint8 public constant decimals = 18;  // 18 is the most common number of decimal places
    // 0.0000000000000000001  个代币

    function totalSupply() external view returns (uint);

    function balanceOf(address tokenOwner) external view returns (uint balance);

    function allowance(address tokenOwner, address spender) external view returns (uint remaining);
    function approve(address spender, uint tokens) external returns (bool success);

    function transfer(address to, uint tokens) external returns (bool success);
    function transferFrom(address from, address to, uint tokens) public returns (bool success);


    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}