Day 21: Reading an account balance in Rust: address(account).balance in Solana

Day 21 of RareSkills Solana Course.

Setup

1. Configure Solana to run on localhost: solana config set --url localhost
2. Run the test validator node on another terminal: solana-test-validator --reset
3. Run Solana logs on another terminal: solana logs
4. Build Anchor program: anchor build
5. Sync program_id with Anchor key: anchor keys sync
6. Run tests: anchor test --skip-local-validator

Notes

• Anchor checks the account being read by default to see if the program owns the account.
• UncheckedAccount bypasses the safety check with reading accounts owned by the program.
• /// CHECK: ... doc comment is required by Anchor when bypassing safety checks like using UncheckedAccount.
• Not all SOL in an account is spendable, a portion of the balance must be maintained to be rent exempt.

References

• UncheckedAccount
• Anchor Accounts Struct Safety Checks
• Sealevel Attacks (common attacks)