The receive function is a special function that is called when someone sends ether to the contract. We will use this function to add participants to the lottery.

receive() external payable {
    require(msg.value == 1 ether, "Exactly 1 ether is required to participate in this Lottery");
    participants.push(payable(msg.sender));
}

In this code, we check that the amount of ether sent is exactly 1 ether, and then we add the sender's address to the "participants" array.

Step 4: Add the getBalance function

We will add a function that allows the manager to check the balance of the contract.

function getBalance() public view returns (uint){
    require(msg.sender == manager, "You don't have access to it.");
    return address(this).balance;
}

In this code, we use the "require" statement to check that the caller is the manager of the contract. If the caller is not the manager, the function will not execute. The function returns the balance of the contract.

Step 5: Add the random function

We will add a function that generates a random number based on the current block's previous block hash, timestamp, and the number of participants in the lottery.

function random() public view returns (uint){
    return uint(keccak256(abi.encode(block.prevhash, block.timestamp, participant.length)));
}

In this code, we use the "keccak256" hash function to generate a random number based on the previous block hash, timestamp, and number of participants. We use the "abi.encode" function to encode the parameters into a byte array that can be passed as an argument to the "keccak256" function. Finally, we convert the hash output into an unsigned integer using the "uint" typecast and return the result.

The purpose of this function is to generate a random number that will be used to determine the winner of the lottery. By including the previous block hash and timestamp, the function ensures that the result is unpredictable and cannot be manipulated by anyone. The number of participants is also included to add some variability to the result, as the outcome of the lottery should depend on the number of participants.

Step 6: Test the contract

We will test the contract by deploying it on the Rinkeby test network and interacting with it using Remix IDE. To do this, we will:

Connect Remix IDE to the Rinkeby test network Compile the contract Deploy the contract Send ether to the contract to participate in the lottery Call the "selectWinner" function to select a winner To connect Remix IDE to the Rinkeby test network, follow the instructions in Step 3. Once you have connected to the Rinkeby test network, compile and deploy the contract.

To participate in the lottery, send at least 1 ether to the contract using the "Send" button in Remix IDE. Make sure to use an Ethereum address that is not the contract manager.

To select a winner, call the "selectWinner" function using the "Transact" button in Remix IDE. Make sure to use the contract manager's address to call this function.

Step 7: Conclusion

In this blog, we have discussed how to create a simple lottery system in Solidity using Remix IDE. Our lottery system is fair and transparent, and it allows anyone to participate by sending ether to the contract. The contract manager is the only person who can select a winner, ensuring that the lottery is conducted in a secure and trustworthy manner.

Smart Contract Code for Ethereum Lottery:-

// SPDX-License-Identifier: GPL-3.0

pragma solidity >= 0.5.0 < 0.9.0;

contract Lottery {

    address public manager;
    address payable[] public participants;

    constructor(){
        manager = msg.sender;
    }

    receive() external payable {
        require(msg.value == 1 ether, "Exactly 1 ether is required to participate in this Lottery");
        participants.push(payable(msg.sender));
    }

    function getBalance() public view returns (uint){
        require(msg.sender == manager, "You don't have access to it.");
        return address(this).balance;
    }

    function random() public view returns (uint){
        return uint(keccak256(abi.encode(block.prevhash, block.timestamp, participants.length)));
    }

    function selectWinner() public{
        require(msg.sender == manager, "Only the manager can select a winner.");
        require(participants.length > 0, "No participants in the Lottery.");

        uint index = random() % participants.length;
        address payable winner = participants[index];
        winner.transfer(getBalance());
        participants = new address payable[](0);
    }
}