How can I append to a fixed size array at different times?

Question

Huge newb here. I want to create multiple arrays that are fixed size arrays of two addresses, but I want to be able to append to the fixed size array from seperate addresses at different times, i.e. after I've switched accounts in Metamask. So from the UI I would click on the approve function that would add msg.sender to the fixed size array, and then once I switched accounts in metamask and clicked on the approve function again, it would add the new msg.sender to the array, giving me a list of arrays that looks like:

0: [msg.sender(from first appprover), msg.sender(from second approver)]
1: [msg.sender, msg.sender]

My current code looks like:

struct Approver {
    uint id;
    address approver;
}

Approver[] public approvers;

And the approve function would look like:

function approveTransfer() external {
    ...
    approver.push(Approver(approver.length, msg.sender));
}

function ApproverList() external view returns(Approver[] memory) {
    return approver;
}

This returns a list of arrays with one address, but I'm trying to get the two. Any help would be greatly appreciated!

Answer 1

You cannot append or push to fixed size arrays because they are already fixed. the memory is alocated to them. see the example bellow.

function memoryArray() external pure{
    uint[] memory newArray = new uint[](5);
    // push is not supported
    newArray[0] = 2;
}

you are pushing approver, which is an address. How ever, approvers is a dynamic array and you can push into it. Making the Approver Array public will automatically makes you a get function. you donn't need a ApproverList() function for that.

how ever you can define the ApproverListfunction like this.

function ApproverList() external view returns(Approver[] memory) {
return approvers;
}  

note that you need to fix this line as well

approver.push(Approver(approvers.length, msg.sender));

you are basically assuming that approver (address) is an array.