Ethereum Cookbook

How to do it...

1. To learn more about reading private variables, consider the following odd-even contract. Each player chooses a number and, if the sum is even, then the first player wins; otherwise, the second player wins:

pragma solidity ^0.4.24;contract OddEven {    struct Player {         address addr;         uint number;    }    Player[2] private players;    uint8 count = 0;    function play(uint number) payable public {        require(msg.value == 1 ether);        players[count] = Player(msg.sender, number);        count++;        if (count == 2) selectWinner();    }    function selectWinner() private {        uint n = players[0].number + players[1].number;        players[n%2].addr.transfer(address(this).balance);        delete players;        count = 0;    } }

2. The contract uses the player's mapping to store previous bets. ...