Interface contact [solidity]

 Introduction to Interface

Interfaces can have only unimplemented functions. Also, they are neither compiled nor deployed. They are also called pure abstract contracts

• Cannot implement any of their functions. All interface functions are implicitly virtual
• Are defined with the keyword interface
• Cannot inherit other contracts or interfaces (after solidity 6.0.0 interfaces can inherit from interfaces) but other contracts can inherit from interfaces
• Function state mutability can be pure , view , payable or default(blank)
• Fallback functions cannot be defined in an Interface
• Interface functions are implicitly "virtual"
• Cannot define a constructor
• Functions can be defined external only
• Cannot have state variables but local variables definition is allowed

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.13;

interface ICounter {

    function count() external view returns (uint);

    function increment() external;

}

contract MyContract {

    function incrementCounter(address _counter) external {

        ICounter(_counter).increment();

    }

    function getCount(address _counter) external view returns (uint) {

        return ICounter(_counter).count();

    }

}