Can I see an example that shows the use of .arrays and push(unint x) method in solidity 0.6?

Question

I'm having problem to understand why the method push() does't work on Remix using Solidity 0.6.

I have read the documentation about arrays fixed size and dynamic size doc reference

for example in this code:

pragma solidity ^0.6.0;

contract Prova
{

   function prova() public{

      uint[] memory array;
      array.push(4);

   }
}

I always get the error: :

TypeError: Member "push" is not available in uint256[] memory outside of storage.

Someone can show me sole example about arrays in solidity. I'm learning. Thanks a lot.

Answer 1

You are trying to use .push with a transient memory instance of an array. It has to be a storage variable.

pragma solidity ^0.6.0;

contract Prova
{
   uint[] public array;

   function prova() public {
      array.push(4);
   }
}

Or, for giggles:

pragma solidity ^0.6.0;

contract Prova
{
   uint[] public array;

   function prova(uint number) public {
      array.push(number);
   }
}

It is declared globally, so storage is implied. I added public so you can inspect it with array(uint row).

Hope it helps.