合约的状态变量可以声明为不可变常数，数值定义后不能再次编辑，可以节约gas fee。有两种定义命令，constant 和 immutable ，区别是constant只支持值类型和字符串，immutable可以；constant必须声明时就赋值，immutable可以推迟到构造函数里赋值 。举例： //1、constant只支持值类型和字符串，immutable可以； address public constant MY_ADDRESS = 0x777788889999AaAAbBbbCcccddDdeeeEfFFfCcCc; uint public constant MY_UINT = 123; string public constant MY_STRING = "123"; bytes public constant MY_BYTES = "123"; address public immutable MY_ADDRESS_IM = 0x777788889999AaAAbBbbCcccddDdeeeEfFFfCcCc; uint public immutable MY_UI...