Common Rust Interview Questions - Part 02

This article will introduce the second part of common Rust interview questions, making it easier for Rust developers to prepare for interviews. Hopefully, these interview questions will be helpful to everyone.

16. What is the unwrap() method in Rust?

The unwrap() method is provided by the Rust programming language’s standard library, and it can extract the value from an Option or Result type while propagating any potential errors that may occur. In Rust, the “Option” and “Result” types are widely used to handle situations where a value may or may not exist, or where an operation may fail due to some error. To access the value within an “Option” or “Result,” you need to use one of the methods provided by these types, such as unwrap(), expect(), map(), match, etc.

17. What are structures in Rust?

A structure, also known as a Structure, is a compound data type that allows you to group related values under a single name. Structures can represent concepts or objects in a program, allowing you to organize data in a more structured way. They are similar to structures in C, classes in C++/Java, or records in Pascal, but they do not have the inherent behavior of classes in object-oriented languages.

18. What is the difference between Option and Result in Rust?

In Rust, both Option and Result are types used to represent the possibility of an error or success. However, they have some differences:

• The “Option” type represents a computation that may or may not produce a value. For example, it is used when a function might not return a value when searching for an item in a collection. The Option can contain either “Some(value)” or “None,” and is typically used to avoid null pointer errors.
• The “Result” type represents the outcome of an operation, which can be either successful or a failure with an associated error value. The Result type is typically used in situations where a function can fail for multiple reasons, allowing for structured error handling.

19. What are procedural macros in Rust?

In Rust, procedural macros are a type of macro that allows you to define custom syntax extensions that can be used in your code. Procedural macros are implemented as Rust functions that take Rust code as input, perform some operation on it, and then generate new Rust code as output. Procedural macros are used for code generation at compile-time.

20. What is a data race in Rust?

A data race in Rust can be defined as a situation where multiple threads (usually more than two) attempt to access the same data or memory location simultaneously, with at least one of the accesses being a write operation. This can lead to undefined behavior, such as data corruption, program crashes, or security vulnerabilities.

21. How does Rust ensure memory safety?

Rust ensures memory safety through two main mechanisms:

• Strict type system: Rust’s type system helps prevent memory safety issues by ensuring type checking at compile-time. This means the compiler can catch many errors before the code runs, such as attempts to access values that have been moved or borrowed.

• Ownership and borrowing system: In Rust, every value has an owner responsible for managing the memory allocated for that value. Rust ensures that a value has only one owner at a time, preventing issues like dangling pointers or use-after-free errors. In addition to ownership, Rust also employs borrowing, which allows functions or methods to temporarily borrow a value owned by another part of the program.

22. What is the cargo.lock file in Rust?

The cargo.lock file contains information related to the dependencies of a Rust project, including transitive dependencies. The purpose of this file is to ensure that anyone building the project will use the same dependencies as the previous version of the project, avoiding dependency conflicts and ensuring reproducible builds.

23. What are enums in Rust?

In Rust, an enum is a type that allows developers to define a set of named values or data. These values can have multiple variants and can also include additional or optional data. In Rust, enums can be used to represent data that can take on a finite set of values, such as days of the week or options in a user interface. They can also be used to define custom error types or other complex data structures.

24. What is conditional compilation in Rust?

Conditional compilation in Rust is a feature that allows developers to selectively compile specific parts of the code based on predefined conditions. This feature is typically used for developing platform-specific code or creating features for specific build configurations. In Rust, conditional compilation is implemented using the #[cfg] attribute. This attribute can specify a condition that determines whether a specific code block should be included in the final compiled binary.

25. What are channels in Rust?

Channels are a mechanism for communication and passing messages between two concurrently executing threads. Channels consist of a sender and a receiver, with a one-way flow of information from the sender to the receiver. Channels in Rust are implemented using the std::sync::mpsc module.

26. What are declarative macros in Rust?

In Rust, declarative macros allow you to define a pattern that matches the input code, and then generate new code based on that pattern. Declarative macros are defined using the macro_rules! macro. The macro_rules! macro takes a set of rules defining patterns to match and the code to generate as input, and generates the code that implements the macro.

27. How do you understand function pointers?

A function pointer is a type that represents a pointer to a function whose identity may be unknown at compile-time. It allows developers to store a reference to a specific function that can be called again within the code. Function pointers are useful when you need to pass a function as an argument to another function or store a function in a data structure. In Rust, you can define function pointers using the fn keyword and the *const or *mut pointer syntax.

28. Explain Tuples in Rust.

A tuple is a collection of values of different types. It is similar to an array, but unlike arrays, tuples can contain values of different types. Tuples are constructed using parentheses, with the values separated by commas. Example: let my_tuple = (10, "hello", true);

29. What is the match statement?

The match statement is a control flow operator that provides a powerful mechanism for transferring control to specific code blocks based on the matching pattern of a variable. It allows you to compare a value against a series of patterns and execute the associated code block for the first matching pattern. When executing a match statement, Rust will attempt each pattern in order and execute the code associated with the first matching pattern.

30. What is the difference between structures and enums in Rust?

While both structs and enums are used to specify custom data types in Rust, they have different properties and purposes. A struct is a data structure that combines different types of related data into a single unit. Structs are typically used to represent entities or objects in a program. Example:

struct Person {
  age: i8,
  name: String
}

An enum is a data type used to represent a set of named values. Enums are typically used to define a finite set of possible states or options for a given value. Each named value in an enum is called a variant. Example:

enum IP {
  IP_V4(String),
  IP_V6(String)
}