Solidity is the popolar popolar Blockchain developer language and many blockchain and crypto projects are using it for developement. Here are common interview questions for Solidity. How can a contract be upgraded after it has been deployed? What are the different function access modifiers available in Solidity? In what situations should events be emitted in Solidity? What is the most gas-efficient method for implementing a double value mapping? What is a common security pitfall in Solidity, and how can it be mitigated? How can you perform multiplication with decimal values using uint types in Solidity? What are the maximum and minimum sizes for uint types in Solidity?

Here are some high-quality Solidity interview questions to sharpen your skills:

(1) Explain the difference between msg.sender, tx.origin, and address(this). This is a common question to test your understanding of how contracts interact in Solidity. msg.sender represents the immediate caller of the function, while tx.origin is the original sender of the entire transaction, which can expose security risks if used improperly. address(this) refers to the current contract instance.

(2) How does Solidity handle inheritance and multiple inheritance conflicts? Solidity uses a directed acyclic graph (DAG) to resolve inheritance, and the order of inheritance is resolved with the “C3 Linearization” algorithm. This prevents conflicts when multiple base contracts have similar or conflicting methods.

(3) What are view and pure functions? view functions are used to read state variables without modifying them, while pure functions don't read or write to any blockchain state. Knowing when to use each is key for writing efficient contracts.

(4) Explain revert(), assert(), and require() statements and their differences. These statements are used for error handling. require() is generally used for validating inputs, assert() for checking invariants, and revert() can roll back transactions with a custom error message.

(5) How do you handle reentrancy attacks in Solidity? To prevent reentrancy, use the "checks-effects-interactions" pattern, where you first check conditions, then update state, and finally interact with external contracts. Also, using ReentrancyGuard from OpenZeppelin is recommended.

For a complete set of Solidity interview questions, including deeper dives into security best practices, optimization techniques, and advanced topics like assembly and gas optimization, I’d recommend studying resources like the Solidity documentation, CryptoZombies, and OpenZeppelin’s resources on secure smart contract development. Good luck, and keep practicing your answers to these questions to handle any curveballs with confidence!

Can anyone explain the differences between require(), revert(), and assert() in Solidity? I want to understand when and why each is used, especially in terms of gas usage and error handling. I understand that each function handles errors, but I am unclear on their specific roles. For instance, I have seen require() check for certain conditions, but I am unsure if revert() or assert() would be appropriate in the same situations.

I also want to know how each impacts gas consumption and whether using one over the other is better practice in different cases. Clear examples or concise explanations would help, particularly focused on real situations in smart contract development.

You can read our latest blog https://artofblockchain.club/article/top-30-interview-questions-for-senior-solidity-developers-in-2025