interview_qa.md

Interview Questions

Q1

• How to implement this Solidity snippet into Solana?

struct Staking {
  bool status,
  uint256 startTimestamp,
  uint256 maturityTimestamp
}

// mapping(user => mapping(id => Staking))
mapping(address => mapping(uint256 => Staking)) userStaking;

A1

• Implement each Staking struct into multiple PDA(s) for different users.
• In order to calculate PDA address, use this:

seeds = [b"staking", seedkey.as_ref(), user.as_ref(), id.to_string().as_bytes()],

where,

seedkey - is constant for the solana program which is used to create unique address.

• Hence, the final data structure looks like this:

// used for the function which is going to use this
#[derive(Accounts)]
#[instruction(seedkey: Pubkey, user: Pubkey, id: u64)]
pub struct userStaking {
	#[account(
	    init,
			seeds = [b"staking", seedkey.as_ref(), user.as_ref(), id.to_string().as_bytes()],
			...
			...
	)]
	pub user_staking: AccountLoader<'a, Staking>,
}

// For PDA
#[account(zero_copy)]
#[derive(Default)]
pub struct Staking {
	pub status: bool,
	pub start_timestamp: u32,
	pub maturity_timestamp: u32
}

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Q2

Is there any way to transfer ownership of any smart contract on solana?

A2

Yes - $ solana program set-upgrade-authority

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Q3

Can we retrieve the program address from within the program code?

A3

Yes - crate::ID

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Q4

Can we define the program address as payer for creating PDA?

A4

No. refer to this troubleshoot issue