Solidity Interview Questions for Intermediate

Explore the list of intermediate interview questions with answers for Solidity. So if you have experience spanning one or two years, then this section is very good for you to upscale your knowledge.

11. What is the constant function in Solidity?

A constant function does not change the state of the contract. Therefore, the constant function can be called from anywhere without concerning the security issues it will impose as the function will not affect the state of the contract.

12. Is it possible to use loops in Solidity?

Yes, one can use loops in Solidity. Solidity supports all necessary loops to make programming easier. One should be careful while using the loops in Solidity.

• Infinite loop results in the loss of the gas and failure to continue executing the contract.
• For loop cannot be used in solidity for iterating over an array.
• If the loop is updating the state of some variables of the contract then extra care should be taken. It should be bounded otherwise the contract can get stuck if the loop iteration is hitting the block’s gas limit.

13. What are hexadecimal literals in Solidity?

Hexadecimal literals are prefixed with hex keyword. These are enclosed in double or single quotes. For example, hex”2AB3F”. Hexadecimal literals have the same convertibility restrictions as string literals. 

14. What are the different Ether units available in Solidity?

The different ether units available in Solidity are wei, kwei, gwei, mwei, microether, milliether, ether.

15. What time units are available in Solidity?

Solidity has time units where the lowest time unit is second and other time units are seconds, minutes, hours, days, and weeks.

16. What are storage variables in Solidity?

Storage variables are the variables that are stored on the blockchain. These variables are permanent and are used for storing important data concerning the contract. They are also known as dynamic variables and are stored in the storage and cannot be changed. They are persistent.

17. What are source files in Solidity?

A solidity source file can contain any number of smart contracts or library definitions in a single file. 

• The source file can contain any number of contract definitions, imports, and pragma.
• It is recommended that a developer maintains different source files for each contract or library definition to have better code maintainability. 
• The solidity source file has .sol extension.

18. What are state variables in Solidity?

State variables are stored in the storage. These values are permanently stored in the contract’s storage. 

•  They store data directly on the blockchain.
• These are declared inside a contract and outside the function.
• These are expensive as they cost gas.
• These can be assigned one of the access modifiers, public, private, or internal.

19. What are the main components of a Solidity Smart Contract?

 The main components of a Solidity smart contract are:

• Pragma statement: This statement specifies the required version of the solidity compiler for the smart contract.
• State variables: These are used to store the contract’s state data persistently on the blockchain.
• Constructor: This is a special function that is used for initializing state variables and called at once at contract deployment.
• Functions: Functions define the logic and behavior of the contract.
• Modifiers: These are the reusable code snippets that can be added to functions to modify their behavior.
• Events: Events are custom data structures that emit transaction logs for external listeners to monitor contract activity and state changes.
• Inheritance: Inheritance allows a contract to inherit properties from a base contract thus enabling code reuse and abstraction.

20. What is special in smart contracts compared to other programs?

• Immutable: Once the smart contracts are deployed on the blockchain, their code cannot be altered. This makes the smart contract invulnerable to unauthorized access.
• Decentralized execution: The execution of smart contracts does not depend on a single authority but instead on multiple nodes that are spread around the world.
• Self-executing: Smart contracts are designed to execute predefined actions automatically when certain conditions specified in the contract are met. This reduces the need for intermediaries thus reducing the potential for human error.
• Tokenization: Smart contracts can be used to create and manage digital assets through the use of tokens.

21. List the difference between unit8 and unit16.

• uint8 stores a number of up to 2^8-1. It has 8 bits.
• uint16 stores number up to 2^16-1. It has 16 bits.

22. What are private and public variables in Solidity?

• Private variables can be accessed only within the contract that declares them. These are not accessible by an external entity nor by the contracts derived from the contract in which they are declared.
• Public variables can be accessed by any contract, function, or external entity. When these variables are declared in Solidity, the compiler automatically generates a getter function that allows any external entity or contract to read its value.

23. List the differences between view and pure functions.

24. List the difference between memory and storage in Solidity.

25. List the differences between struct and array.

26. How much is 1 gwei of Ether?

1 Gwei equals 0.000000001 or 10e-9 ETH. 1 ETH equals one billion (10e9) Gwei.

27. How much is 1 wei of Ether?

1 wei is equivalent to 10^-18 ETH. 1 ETH is equal to 1,000,000,000,000,000,000 wei/

28. How much is 1 kwei of Ether?

1 kwei is equal to 0.00000000 ETH.

Solidity is an object-oriented programming language used to implement smart contracts on blockchain platforms like Ethereum, which generates transaction records in the system. To excel in your journey toward top companies as a Solidity developer, you need to master some important Solidity Interview Questions to crack their Solidity Online Assessment Round and Solidity Interview Round. We have prepared a list of the Top 50 Solidity Interview Questions along with their answers to ace in interviews.

In this article, we have covered all the essential questions that are likely to be asked in interviews, whether you are a beginner embarking on your journey to become a Solidity Engineer/developer or a seasoned professional seeking a job change and aiming to refresh important concepts in line with current trends. Then this Interview guide is for you.

This Solidity Interview Questions article is designed for all skill levels, from beginners and intermediates to advanced candidates, encompassing a wide range of interview questions.