Chendi Wu

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solidity ​

datatype ​

solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2 <0.9.0;

contract ArrayType {
    uint8[3] data;

    uint8[] ddata;

    // function testStaticArray1() internal view returns (uint8[3] storage) {
    //     return data;
    // }

    // function testStaticArray2() public view returns (uint8[3] memory) {
    //     // data[0] = 25;
    //     return data;
    // }

    function testStaticArray() public returns (uint8[3] memory) {
        data[0] = 25;
        return data;
    }

    function testReadDynamicStorageArray()
        public
        view
        returns (uint8[] memory)
    {
        return ddata;
    }

    function testWriteDynamicStorageArray() public {
        ddata.push(32);
        ddata.pop();
        ddata.push(60);
    }

    function testMemoryDynamicArra(
        uint8 size
    ) public pure returns (uint8[] memory) {
        uint8[] memory mdata = new uint8[](size + 1);
        // for (uint8 i = 0; i < size; i++) {
        //     mdata[i] = i;
        // }
        // mdata.push(67);
        return mdata;
    }
}
solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2 <0.9.0;

contract BasicType {
    function testInt() public pure returns (uint256) {
        uint8 i8_0 = 12;
        uint8 i8_1 = 0;
        uint8 i8_2 = 8;
        // uint8 i8_3 = -1;
        uint8 i8_4 = 255;
        // uint8 i8_5 = 256;
        // i8_4++;

        uint8 x = 8;
        uint16 y = 9;
        // x = y; // error
        // 强制类型转换
        // x = uint8(y);
        y = x;

        uint256 i256_1 = 255;
        i256_1++;
        uint256 max = type(uint256).max;
        return max;
        // 115792089237316195423570985008687907853269984665640564039457584007913129639935
    }

    enum OrderState {
        layorder,
        paymen
    }

    function enumTest() public view returns (OrderState) {
        OrderState state = OrderState.layorder;
        // OrderState state = OrderState.paymen;
        return state;
    }
}
solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2 <0.9.0;

contract BytesAndString {
    // 初始化方式 new
    string name = "BytesAndString"; // new string(5);
    bytes name1 = "BytesAndString1"; // new bytes(5);

    // bytes memory name1 = bytes("BytesAndString1");
    // bytes memory name1 = bytes(abi.encodePacked("BytesAndString1"));

    // string 是不能修改的, bytes 是可以修改的

    function testStringAndBytes() public view returns (string memory) {
        // 初始化方式 new
        // 为什么用 new ?
        // struct 初始化为什么不用 new ?
        string memory data = "xyz";
        bytes memory data1 = "cd";

        // 不同 location 的 memory 拷贝
        data = name;
        data1 = name1;

        // 类型转换
        data1 = bytes(data);
        data = string(data1);
        // 下标访问
        bytes1 b = data1[0];
        data1[0] = 0x88;
        // bytes(data)[0] = 0x88;

        // name1.push(0x00);
        // data1.push(0x00);
        return data;
    }

    // bytes 与 byte1[] 的区别
}
solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2 <0.9.0;

contract ComplexValueType {
    function testAddress() public view returns (address) {
        address addr = msg.sender;
        // 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4
        // 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4

        return addr;
    }

    function testMyAddress() public view returns (address) {
        address addr = address(this);

        // 0x5FD6eB55D12E759a21C09eF703fe0CBa1DC9d88D
        // 0x5FD6eB55D12E759a21C09eF703fe0CBa1DC9d88D
        return addr;
    }

    // Contract Type
    // function testContract() public view {
    //     ComplexValueType myContract = this;
    // }

    function testFixedByteArray() public pure returns (bytes3) {
        // default: 0x000000
        bytes3 data = 0x111111;
        return data;
    }

    function testFixedByteArray1() public pure returns (bytes1) {
        // default: 0x000000
        bytes3 data = 0x111111;

        // 0x11
        bytes1 first = data[0];
        return first;
    }
}
solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2 <0.9.0;

contract MappingType {
    mapping(string => uint8) public ages;
    mapping(string => mapping(string => uint8)) public ages1;

    function getAge(string memory name) public view returns (uint8) {
        return ages[name];
    }

    function setAge(string memory name, uint8 age) public {
        // mapping(string => uint8) storage myages = ages;
        ages[name] = age;
    }

    // 一般规则: public menory calldata internal private 可以是 storage
    // mapping: 只能是 storage
    //  => public 函数参数或者返回值不可能出现 mapping 类型

    // 写一个 internal 或者 private 函数，传递 storage 的 mapping
    // function setAge1(
    //     mapping(string => uint8) storage myages,
    //     string memory name,
    //     uint8 age
    // ) internal {
    //     myages[name] = age;
    // }
}
solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2 <0.9.0;

contract StructType {
    struct Person {
        string name;
        uint8 age;
        Home home;

        // Person bestFriend;
        // 测试递归
    }

    Person master;

    struct Home {
        string country;
        string province;
        string city;
    }

    // 测试 struct 作为参数
    function readPerson() public view returns (Person memory) {
        return master;
    }

    function writePerson(Person memory p) public {
        master = p;
    }

    function writePersonName(string memory name) public {
        master.name = name;
    }

    // 测试内存 struct. 对 struct 来说，memory 与 storage 并没有大的影响
    function testMemoryStruct() public pure returns (Person memory) {
        // Person memory p = Person(
        //     "zhangsan",
        //     18,
        //     Home("China", "Shanghai", "Shanghai")
        // );
        // return p;
        Person memory p;
        p.name = "cd";
        p.age = 28;

        return p;
    }

    // 测试内存 location 为 storage 的局部变量
    function testStorageLocalStruct() public view returns (Person memory) {
        Person storage p = master;

        // p.name = "dd";
        // p.age = 29;

        return p;
    }
}

contracts ​

solidity
// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.8.2 <0.9.0;

contract BanlanceManager {
    mapping(address => uint256) public balanceOf;

    string public name = "MYDOLLAR";
    string public symbol = "$";
    uint8 public decimals = 4;

    constructor(uint256 totalBalance) {
        balanceOf[msg.sender] = totalBalance;
    }

    function transfer(
        // address from,
        address to,
        uint256 amount
    ) public {
        address from = msg.sender;
        uint256 fb = balanceOf[from];
        uint256 tb = balanceOf[to];

        require(amount <= fb, "Insufficient balance");

        fb -= amount;
        tb += amount;
        balanceOf[from] = fb;
        balanceOf[to] = tb;
    }
}

// 0x3261f5Fe789eB2780062B8cc3a98e947ac9F801B
// 0x380d495A265ACd2D1D6c506d28CD70FA7610f8B2

// 0x6Ad1B2dD054eB74F4CeBbC6D5681062A250189C5