发行ERC20的代币。先上代码，后续补充部署和代码注释说明
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address recipient, uint256 amount) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address owner, address spender) external view returns (uint256);
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
}
contract ERC20 is IERC20 {
// 总发行的货币量
uint256 public totalSupply;
mapping(address => uint) public balanceOf;
mapping(address => mapping(address => uint)) public allowance;
string public name = "BT";
string public symbol = "BPC";
uint8 public decimals = 18;
function transfer(address recipient, uint256 amount) external returns (bool){
balanceOf[msg.sender] -= amount;
balanceOf[recipient] += amount;
emit Transfer(msg.sender,recipient,amount);
return true;
}
function approve(address spender, uint256 amount) external returns (bool) {
allowance[msg.sender][spender] = amount;
emit Approval(msg.sender,spender,amount);
return true;
}
function transferFrom(address sender, address recipient, uint256 amount) external returns (bool) {
allowance[sender][msg.sender] -= amount;
balanceOf[sender] -= amount;
balanceOf[recipient] += amount;
emit Transfer(sender, recipient, amount);
return true;
}
function mint(uint amount) external {
balanceOf[msg.sender] +=amount;
totalSupply += amount;
emit Transfer(address(0),msg.sender,amount);
}
function burn(uint amount) external {
balanceOf[msg.sender] -= amount;
totalSupply -= amount;
emit Transfer(msg.sender,address(0),amount);
}
}