Solidity : Error when pushing an address into a dynamic address type array

Question

I'm trying to insert an address into an address type dynamic array. It works well when I do the operation inside a function. There are no errors and the elements are properly pushed into the array.

pragma solidity ^0.5.2;

contract Random {
    address[] public participants;

    function addParticipant() public {
        participants.push(0xCA35b7d915458EF540aDe6068dFe2F44E8fa733c);
        participants.push(0x583031D1113aD414F02576BD6afaBfb302140225);
        participants.push(0xdD870fA1b7C4700F2BD7f44238821C26f7392148);
    }
}

But when I try to do it without a function it shows an error.

Error: Expected identifier but got '('

pragma solidity ^0.5.2;

contract Random {
    address[] public participants;

    // function addParticipant() public {
        participants.push(0xCA35b7d915458EF540aDe6068dFe2F44E8fa733c);
        participants.push(0x583031D1113aD414F02576BD6afaBfb302140225);
        participants.push(0xdD870fA1b7C4700F2BD7f44238821C26f7392148);
    // }    
}

Please advise.

Answer 1

You can only declare state variables and set initial values outside of functions. No processing. This is mapping out how storage slots will be assigned and possibly setting value, but no more.

However, you can define a constructor to run once when the contract is deployed. This is the appropriate place for an initialization process.

address[] public array;

constructor() public {
  array.push( ...
}

Hope it helps.