区块链入门到实战（35）之Solidity – 变量作用域

pragma solidity ^0.5.0;
contract C {
   uint public data = 30;
   uint internal iData= 10;

   function x() public returns (uint) {
      data = 3; // 内部访问
      return data;
   }
}
contract Caller {
   C c = new C();
   function f() public view returns (uint) {
      return c.data(); // 外部访问
   }
}
contract D is C {
   uint storedData; // 状态变量

   function y() public returns (uint) {
      iData = 3; // 派生合约内部访问
      return iData;
   }
   function getResult() public view returns(uint){
      uint a = 1; // 局部变量
      uint b = 2;
      uint result = a + b;
      return storedData; // 访问状态变量
   }
}