Solidity零基础学习心得

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

contract Counter {
    uint public count;                      unit这个也就是字符串非负整数

    // Function to get the current count
    function get() public view returns (uint) {	   当前这一段的意思是：通过当前这段话读取前一句的count
        return count;
    }

    // Function to increment count by 1
    function inc() public {
        count += 1;
    }

    // Function to decrement count by 1
    function dec() public {
        // This function will fail if count = 0
        count -= 1;
    }
}

Boolean    布尔
Uint			非负整数
Int			整数
Address		地址
1、新建一个合约
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract Primitives {————————————Primitives合约的名称
    bool public boo = true;———————— bool（布尔）是solidity中的逻辑字符号（true/false）初始默认值是False
    /*
    uint stands for unsigned integer, meaning non negative integers
    different sizes are available
        uint8   ranges from 0 to 2 ** 8 - 1
        uint16  ranges from 0 to 2 ** 16 - 1
        ...
        uint256 ranges from 0 to 2 ** 256 - 1
    */
														Uint8是非负整数类型，最大值是2的8方-1（255）范围就是零到255
														Unit16 是2**16-1(65535)，范围就是0~65535
Unit默认值也就是最大值最大范围2**256-1
    uint8 public u8 = 1;
    uint public u256 = 456;
    uint public u = 123; // uint is an alias for uint256

    /*
    Negative numbers are allowed for int types.
    Like uint, different ranges are available from int8 to int256
    
    int256 ranges from -2 ** 255 to 2 ** 255 - 1
    int128 ranges from -2 ** 127 to 2 ** 127 - 1
    */
    int8 public i8 = -1;
    int public i256 = 456;
    int public i = -123; // int is same as int256
												Int8是整数类型，最小值是-2**7最大值2**7-1共256个数字
    // minimum and maximum of int
    int public minInt = type(int).min;
    int public maxInt = type(int).max;

    address public addr =    0xCA35b7d915458EF540aDe6068dFe2F44E8fa733c;
		addr=就是地址的意思，交互对象账号地址

    /*
    In Solidity, the data type byte represent a sequence of bytes. 
    Solidity presents two type of bytes types :

     - fixed-sized byte arrays
     - dynamically-sized byte arrays.
     
     The term bytes in Solidity represents a dynamic array of bytes. 
     It’s a shorthand for byte[] .
    */
    bytes1 a = 0xb5; //  [10110101]
    bytes1 b = 0x56; //  [01010110]

    // Default values
    // Unassigned variables have a default value
    bool public defaultBoo; // false
    uint public defaultUint; // 0
    int public defaultInt; // 0
    address public defaultAddr; // 0x0000000000000000000000000000000000000000
				Bytes代表字节 （没整明白）

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

contract Variables {
    // State variables are stored on the blockchain.
    string public text = "Hello";
    uint public num = 123;

    function doSomething() public {
        // Local variables are not saved to the blockchain.
        uint i = 456;

        // Here are some global variables
        uint timestamp = block.timestamp; // Current block timestamp   这个叫时间戳，上面这句话意思是1970年距离今天的秒数
        address（地址的意思开头） sender = msg.sender; // address of the caller      msg.sender调用当前的地址
    }
}
555、constant（常量）
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
//constant就相当于使后面的变量不能被修改的，这样储存的时候可以减少GAS消耗
contract Constants {
    // coding convention to uppercase constant variables
    address public constant MY_ADDRESS = 0x777788889999AaAAbBbbCcccddDdeeeEfFFfCcCc;
    	// constant后面紧跟的值必须是大
    uint public constant MY_UINT = 123;
}

Reading and Writing to a State Variable
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract SimpleStorage {           定义一个变量，SimpleStorage（简单储存）
    // State variable to store a number
    uint public num;  //在区块链上部署了一个名为num的变量，占用一个位置

    // You need to send a transaction to write to a state variable.
    function set(uint _num) public {       这一段里面的_name是自己随便设置一个变量名字只是为了下面提取跟name一样的值
        num = _num;
    }

    // You can read from a state variable without sending a transaction.
    function get() public view returns (uint) {
        return num;
    }
}

uint public oneEther = 1 ether;
// 1 ether is equal to 10^18 wei
bool public isOneEther = 1 ether == 1e18;