Visibility and Privacy

Visibility controls which Solidity code can access a declaration through language-level interfaces. private state can be used by the contract that declares it, while public state adds a getter. Neither modifier encrypts blockchain data or makes a stored password safe.

Declare this at contract scope:

uint256 private referenceId;

Use it inside the provided main function:

referenceId = 38;
console.log(referenceId);

main can access the private variable because it belongs to the same contract. A separate contract cannot read it through a generated public getter, but blockchain observers can still inspect storage. These exercises teach language fundamentals, not a production security design.

private limits direct Solidity access; it does not provide confidentiality on a public blockchain.