Interfaces

Interface define functions in a contract and is also created using the keyword interface.

Interface characteristics

• An interface can not have any function with implementation.
• Functions of an interface can only be of type external.
• An interface can not have a constructor.
• An interface can not have state variables.
• An interface can have enum, structs which can be accessed using interface name dot notation.

pragma solidity ^0.8.4;

interface Calculator {
   function getResult() external view returns(uint);
}
contract Test is Calculator {
   constructor() public {}
   function getResult() external view returns(uint){
      uint a = 1; 
      uint b = 2;
      uint result = a + b;
      return result;
   }
}