05-2-Create_ERC20_token

1.Create your own ERC20 token

Using Open Zeppelin it's really easy to create your own ERC20 token.

Here is an example

使用Open Zeppelin可以非常轻松地创建您自己的 ERC20 代币。 这是一个例子:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.0.0/contracts/token/ERC20/ERC20.sol";

contract MyToken is ERC20 {
    constructor(string memory name, string memory symbol) ERC20(name, symbol) {
        // Mint 100 tokens to msg.sender
        // Similar to how
        // 1 dollar = 100 cents
        // 1 token = 1 * (10 ** decimals)
        _mint(msg.sender, 100 * 10 ** uint(decimals()));
    }
}

2.交换代币的合约

以下是一个合约示例TokenSwap，用于将一种 ERC20 代币交易为另一种代币。

该合约将通过调用交换代币

transferFrom(address sender, address recipient, uint256 amount)

这会将amount代币从转移sender到recipient。

要想transferFrom成功，sender必须

• amount余额中多于代币
• 允许通过调用TokenSwap提取代amount币approve

For transferFrom to succeed, sender must

have more than amount tokens in their balance allowed TokenSwap to withdraw amount tokens by calling approve

prior to TokenSwap calling transferFrom:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.0.0/contracts/token/ERC20/IERC20.sol";

/*
How to swap tokens

1. Alice has 100 tokens from AliceCoin, which is a ERC20 token.
2. Bob has 100 tokens from BobCoin, which is also a ERC20 token.
3. Alice and Bob wants to trade 10 AliceCoin for 20 BobCoin.
4. Alice or Bob deploys TokenSwap
5. Alice approves TokenSwap to withdraw 10 tokens from AliceCoin
6. Bob approves TokenSwap to withdraw 20 tokens from BobCoin
7. Alice or Bob calls TokenSwap.swap()
8. Alice and Bob traded tokens successfully.
*/

contract TokenSwap {
    IERC20 public token1;
    address public owner1;
    uint public amount1;
    IERC20 public token2;
    address public owner2;
    uint public amount2;

    constructor(
        address _token1,
        address _owner1,
        uint _amount1,
        address _token2,
        address _owner2,
        uint _amount2
    ) {
        token1 = IERC20(_token1);
        owner1 = _owner1;
        amount1 = _amount1;
        token2 = IERC20(_token2);
        owner2 = _owner2;
        amount2 = _amount2;
    }

    function swap() public {
        require(msg.sender == owner1 || msg.sender == owner2, "Not authorized");
        require(
            token1.allowance(owner1, address(this)) >= amount1,
            "Token 1 allowance too low"
        );
        require(
            token2.allowance(owner2, address(this)) >= amount2,
            "Token 2 allowance too low"
        );

        _safeTransferFrom(token1, owner1, owner2, amount1);
        _safeTransferFrom(token2, owner2, owner1, amount2);
    }

    function _safeTransferFrom(
        IERC20 token,
        address sender,
        address recipient,
        uint amount
    ) private {
        bool sent = token.transferFrom(sender, recipient, amount);
        require(sent, "Token transfer failed");
    }
}