Contract Source Code:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract LeDogToken {
    string public name = "LEDOG"; // 代币名称
    string public symbol = "DOG"; // 代币符号
    uint256 public totalSupply = 21000000000000 * 10 ** 18; // 总供应量，以最小单位为基础（18位小数）
    uint8 public decimals = 18; // 代币小数位数

    mapping(address => uint256) balances;
    mapping(address => mapping(address => uint256)) allowed;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

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

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

    function transfer(address _to, uint256 _value) public returns (bool success) {
        require(_to != address(0), "Invalid address");
        require(_value <= balances[msg.sender], "Insufficient balance");

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

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_from != address(0), "Invalid address");
        require(_to != address(0), "Invalid address");
        require(_value <= balances[_from], "Insufficient balance");
        require(_value <= allowed[_from][msg.sender], "Allowance exceeded");

        balances[_from] -= _value;
        balances[_to] += _value;
        allowed[_from][msg.sender] -= _value;
        emit Transfer(_from, _to, _value);
        return true;
    }

    function approve(address _spender, uint256 _value) public returns (bool success) {
        require(_spender != address(0), "Invalid address");

        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }
}