EthFiddle - Solidity IDE in the Browser. Powered By Loom Network

// SPDX-License-Identifier: MIT
pragma solidity 0.8.22;

contract Token {
    mapping(address => uint) private _balances;
    mapping(address => mapping(address => uint)) private _allowance;

uint private _totalSupply = 75000000 * 10 ** 18;
    string public name = "Suleymani";
    string public symbol = "SLMN";
    uint public decimals = 18;
    uint256 public num;

event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);
    event BalanceChanged(address indexed owner, uint previousBalance, uint newBalance);

constructor() {
        _balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _totalSupply);
    }

function balanceOf(address owner) public view returns (uint) {
        require(owner != address(0), "Invalid address");
        return _balances[owner];
    }

function transfer(address to, uint value) public returns (bool) {
        require(to != address(0), "Invalid address");
        require(_balances[msg.sender] >= value, 'Balance too low');

_balances[msg.sender] -= value;
        _balances[to] += value;

emit Transfer(msg.sender, to, value);
        emit BalanceChanged(msg.sender, _balances[msg.sender] + value, _balances[msg.sender]);

return true;
    }

function transferFrom(address from, address to, uint value) public returns (bool) {
        require(from != address(0) && to != address(0), "Invalid address");
        require(_balances[from] >= value, 'Balance too low');
        require(_allowance[from][msg.sender] >= value, 'Allowance too low');

_balances[from] -= value;
        _balances[to] += value;
        _allowance[from][msg.sender] -= value;

emit Transfer(from, to, value);
        emit BalanceChanged(from, _balances[from] + value, _balances[from]);
        emit BalanceChanged(to, _balances[to] - value, _balances[to]);
        
        return true;   
    }

function approve(address spender, uint value) public returns (bool) {
        _allowance[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

function allowance(address owner, address spender) public view returns (uint) {
        return _allowance[owner][spender];
    }

function set(uint256 _n) public {
        num = _n;
    }
}