Mengimplementasikan Token
transfer dan approve
Mengimplementasikan Token adalah pelajaran Web3 & DApp Development Fundamentals gratis di CoddyKit. Ini adalah pelajaran 2 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar Web3 & DApp Development Fundamentals, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus Web3 & DApp Development Fundamentals mencakup 4 pelajaran total.
Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.
Building a Token
Now you will implement the core of an ERC-20 token from scratch. Understanding the internals helps you debug and audit real tokens, even when you later use libraries.
We will focus on the state, transfer, and approve.
Core State Variables
A token needs to track balances and total supply. Balances are stored in a mapping from address to amount.
<code>contract Token {
string public name = 'MyToken';
string public symbol = 'MTK';
uint8 public decimals = 18;
uint256 public totalSupply;
mapping(address => uint256) public balanceOf;
}</code>The Constructor
The constructor mints an initial supply to the deployer. We increase totalSupply and credit the creator's balance.
<code>constructor(uint256 initialSupply) {
totalSupply = initialSupply;
balanceOf[msg.sender] = initialSupply;
}</code>The Events
Declare the two required events. We will emit Transfer on every movement and Approval when an allowance is set.
<code>event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);</code>Implementing transfer
The transfer function moves tokens from the caller to a recipient. It must check the caller has enough balance and emit the Transfer event.
<code>function transfer(address to, uint256 amount) public returns (bool) {
require(balanceOf[msg.sender] >= amount, 'insufficient balance');
balanceOf[msg.sender] -= amount;
balanceOf[to] += amount;
emit Transfer(msg.sender, to, amount);
return true;
}</code>Guarding Against Zero Address
Sending tokens to address(0) effectively destroys them by accident. Many implementations reject it explicitly.
<code>function transfer(address to, uint256 amount) public returns (bool) {
require(to != address(0), 'transfer to zero');
require(balanceOf[msg.sender] >= amount, 'insufficient');
balanceOf[msg.sender] -= amount;
balanceOf[to] += amount;
emit Transfer(msg.sender, to, amount);
return true;
}</code>The allowance Mapping
To support delegated transfers we add a nested mapping: owner to spender to approved amount.
<code>mapping(address => mapping(address => uint256)) public allowance;</code>Implementing approve
The approve function lets the caller authorize a spender to move up to a certain amount of their tokens. It records the allowance and emits Approval.
<code>function approve(address spender, uint256 amount) public returns (bool) {
allowance[msg.sender][spender] = amount;
emit Approval(msg.sender, spender, amount);
return true;
}</code>Overflow Safety
Since Solidity 0.8, arithmetic reverts on overflow and underflow automatically. The subtraction in transfer is safe: if the balance is too low it reverts, though the explicit require gives a clearer error.
Why Return bool
The standard specifies a bool return for compatibility. We return true on success. On failure we revert, which is the modern convention and safer than silently returning false.
Putting It Together
With state, events, transfer, and approve in place you have a functioning fungible token. The next lesson adds transferFrom to complete the allowance flow.
<code>// state + constructor + events + transfer + approve
// = a minimal working ERC-20</code>Quick Check
Test your understanding of implementing a token.
Recap
You implemented the core of an ERC-20 token:
- State: name, symbol, decimals, totalSupply, balanceOf mapping
- Constructor mints the initial supply to the deployer
transferchecks balance, updates state, emitsTransferapproverecords an allowance and emitsApproval- Guard against the zero address and rely on 0.8 overflow safety
Pertanyaan yang Sering Diajukan
Apakah pelajaran “Mengimplementasikan Token” gratis?
Ya — teks lengkap “Mengimplementasikan Token” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus Web3 & DApp Development Fundamentals, upgrade ke CoddyKit PRO. Kursus Web3 & DApp Development Fundamentals mencakup 4 pelajaran total.
Apa yang akan aku pelajari di “Mengimplementasikan Token”?
transfer dan approve Kamu berlatih Web3 & DApp Development Fundamentals dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.
Apakah aku perlu pengalaman untuk memulai Web3 & DApp Development Fundamentals?
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Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.
Bisakah aku menulis dan menjalankan kode dalam pelajaran Web3 & DApp Development Fundamentals ini?
Ya. Setiap pelajaran Web3 & DApp Development Fundamentals menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.
Semua pelajaran dalam kursus ini
- Standar ERC-20
- Mengimplementasikan Token
- Allowance
- Minting dan Burning