pragma solidity 0.5.1; //specifies version of solidity

contract SimpleCounter {//Doesn't have to match file name
    int counter;// State variable gets stored in a node in Blockchain
    //or: int public counter;
        //public here automatically creates a getter function like the function below
    //initialize variable with constructor
    constructor() public{//Public means anyone can invoke this contract
        counter = 0;
    }

    function getCounter() view public returns (int){//View is like constant keyword. Function does not modify state
        //returns integer
        return counter;
    }

    function increment() public{
        counter += 1;
    }

    function decrement() public{
        counter -= 1;
    }

    //Gas is a unit of computation used to change the state of the contract. Gas translates to ether you
    //need to pay when somene invokes a function
}
//Etherum stores the entire state of your program on the Blockchain
//Smart contracts are programs that you can interact switch