Blockchain Developer FREE Blockchain Developer Smart Contract Development Questions and Answers 2

Question 1

What is the primary purpose of the 'require' statement in Solidity smart contracts?

Accepted Answer

To validate conditions and revert the transaction if not met

Answer

The 'require' statement checks a condition and reverts the entire transaction with remaining gas refunded if the condition evaluates to false.

Question 2

Which design pattern is used to allow upgrading smart contract logic while preserving stored data?

Accepted Answer

Proxy pattern

Answer

The proxy pattern delegates calls to an implementation contract, allowing the logic to be swapped while the proxy retains all state and the same address.

Question 3

What happens when a smart contract function marked as 'view' attempts to modify state?

Accepted Answer

The compiler throws an error

Answer

The Solidity compiler enforces that 'view' functions cannot modify state and will produce a compilation error if state modification is attempted.

Question 4

In Solidity, what is the maximum size of a deployed smart contract's bytecode on Ethereum mainnet?

Accepted Answer

24,576 bytes

Answer

EIP-170 introduced a contract size limit of 24,576 bytes (24 KB) to prevent denial-of-service attacks on the network.

Question 5

Which vulnerability occurs when a contract makes an external call before updating its own state?

Accepted Answer

Reentrancy attack

Answer

Reentrancy occurs when an external call allows the called contract to re-enter the calling function before state updates are completed.

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Blockchain Developer FREE Blockchain Developer Smart Contract Development Questions and Answers 2