token_zago.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.2;

interface IERC20 {
    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 transfer(address to, uint tokens) external returns (bool success);
    function approve(address spender, uint tokens) external returns (bool success);
    function transferFrom(address from, address to, uint tokens) external returns (bool success);

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

contract DIOZCoin is IERC20 {

    string public constant name = "DIO Zago Coin";
    string public constant symbol = "DIZ" ;
    uint constant public decimals = 2;
    uint256 public _totalSupply = 1000000;

    mapping(address => uint) balances;
    mapping(address => mapping(address => uint)) allowed;

    constructor() {
        balances[msg.sender] = _totalSupply;
    }

    function totalSupply() public override view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address tokenOwner) public override view returns (uint256) {
        return balances[tokenOwner];
    }

    function transfer(address to, uint tokens) public override returns (bool success) {
        require(tokens <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender] - tokens;
        balances[to] = balances[to] + tokens;
        emit Transfer(msg.sender, to, tokens);
        return true;
    }

    function approve(address spender, uint256 tokens) public override returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        return true;
    }

    function allowance(address tokenOwner, address spender) public override view returns (uint256) {
        return allowed[tokenOwner][spender];
    }

    function transferFrom(address from, address to, uint256 tokens) public override returns (bool) {
        require(tokens <= balances[msg.sender]);
        require(tokens <= allowed[from][msg.sender]);

        balances[from] = balances[from] - tokens;
        allowed[from][msg.sender] = allowed[from][msg.sender] - tokens;
        balances[to] = balances[to] + tokens;
        emit Transfer(from, to, tokens);
        return true;
    }
}