铸造与销毁
管理供应量
铸造与销毁 是 CoddyKit 上的免费 Web3 & DApp Development Fundamentals 课时。 这是第 4 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 Web3 & DApp Development Fundamentals 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Web3 & DApp Development Fundamentals 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
Managing Supply
Minting creates new tokens and burning destroys them. Together they let a token's totalSupply grow or shrink over time.
These operations are not part of the core ERC-20 interface, but they are extremely common extensions.
What Minting Does
Minting increases totalSupply and credits new tokens to a recipient's balance. It is how tokens enter circulation - at deployment, as rewards, or on demand.
Implementing Mint
A mint function adds to both totalSupply and the recipient's balance, then emits a Transfer event from the zero address.
<code>function _mint(address to, uint256 amount) internal {
require(to != address(0), 'mint to zero');
totalSupply += amount;
balanceOf[to] += amount;
emit Transfer(address(0), to, amount);
}</code>Mint Emits From Zero
By convention a mint is logged as a Transfer from address(0). Wallets and indexers interpret a transfer originating at the zero address as new tokens being created.
<code>emit Transfer(address(0), to, amount); // signals minting</code>What Burning Does
Burning reduces totalSupply and subtracts from a holder's balance, permanently removing tokens from circulation. It is used for deflationary mechanics, redemptions, and buybacks.
Implementing Burn
A burn function checks the holder's balance, decreases it and totalSupply, then emits a Transfer to the zero address.
<code>function _burn(address from, uint256 amount) internal {
require(balanceOf[from] >= amount, 'burn exceeds balance');
balanceOf[from] -= amount;
totalSupply -= amount;
emit Transfer(from, address(0), amount);
}</code>Burn Emits To Zero
Symmetrically, a burn is logged as a Transfer to address(0). Tokens sent to the zero address are unrecoverable, which is exactly the intent.
<code>emit Transfer(from, address(0), amount); // signals burning</code>Access Control on Mint
Minting must be restricted - an open mint function lets anyone create unlimited tokens, destroying value. Gate it behind an owner or minter role.
<code>address public owner;
modifier onlyOwner() { require(msg.sender == owner, 'not owner'); _; }
function mint(address to, uint256 amount) public onlyOwner {
_mint(to, amount);
}</code>Burning Your Own Tokens
Holders are usually allowed to burn their own tokens freely. A public burn simply burns from msg.sender.
<code>function burn(uint256 amount) public {
_burn(msg.sender, amount);
}</code>Capped Supply
To guarantee scarcity, a token can enforce a maximum supply by checking against a cap before minting.
<code>uint256 public immutable cap;
function mint(address to, uint256 amount) public onlyOwner {
require(totalSupply + amount <= cap, 'cap exceeded');
_mint(to, amount);
}</code>Burn From Allowance
Like transferFrom, a burnFrom lets an approved spender burn another account's tokens, decrementing the allowance first.
<code>function burnFrom(address from, uint256 amount) public {
require(allowance[from][msg.sender] >= amount, 'allowance');
allowance[from][msg.sender] -= amount;
_burn(from, amount);
}</code>Quick Check
Test your understanding of minting and burning.
Recap
You learned supply management:
- Mint increases totalSupply, credits a balance, emits Transfer from address(0)
- Burn decreases totalSupply, debits a balance, emits Transfer to address(0)
- Minting must be access-controlled; holders can usually burn their own tokens
- Caps enforce a maximum supply; burnFrom uses allowances
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常见问题解答
「铸造与销毁」课时是免费的吗？
是的 — 「铸造与销毁」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Web3 & DApp Development Fundamentals 课程的其余内容，请升级到 CoddyKit PRO。 Web3 & DApp Development Fundamentals 课程共包含 4 节课。
「铸造与销毁」这节课中我会学到什么？
管理供应量 你通过在浏览器中直接运行的动手代码来练习 Web3 & DApp Development Fundamentals，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 Web3 & DApp Development Fundamentals 需要有经验吗？
无需任何先前经验。CoddyKit 上的 Web3 & DApp Development Fundamentals 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 4 节课，共 4 节。
「铸造与销毁」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 Web3 & DApp Development Fundamentals 课中编写并运行代码吗？
能。每节 Web3 & DApp Development Fundamentals 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。