Syntax Quiz - Languages Rust

Free practice quiz: Syntax (Languages Rust). 52 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. In Rust, what keyword is used to declare a mutable variable?

   1. let
   2. mut
   3. var
   4. const
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   Answer: B. mut

   Variables in Rust are immutable by default. To make a variable mutable, you must prefix the `let` binding with the `mut` keyword. For example: `let mut x = 5;`.

2. Which keyword is used to define a constant in Rust?

   1. let
   2. const
   3. static
   4. var
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   Answer: B. const

   Constants in Rust are declared using the `const` keyword. They must be annotated with their type and have a value that can be determined at compile time. They are always immutable.

3. What does the `struct` keyword define in Rust?

   1. A function that can return multiple values.
   2. A collection of related data, similar to a class.
   3. A type that can represent a single value from a set of possible values.
   4. A reference to another data structure.
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   Answer: B. A collection of related data, similar to a class.

   `struct` is used to define custom data types that group together multiple related values. These are analogous to structures in C or classes in other object-oriented languages.

4. What is the purpose of the `impl` keyword in Rust?

   1. To define a new trait.
   2. To define a type alias.
   3. To implement methods for a struct or enum, or to implement a trait for a type.
   4. To create a generic function.
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   Answer: C. To implement methods for a struct or enum, or to implement a trait for a type.

   `impl` is used to define implementation blocks, which contain methods associated with a particular type (struct or enum) or to implement a trait for a type.

5. What is a `HashMap` in Rust used for?

   1. Storing ordered sequences of elements.
   2. Storing key-value pairs where keys are unique.
   3. Storing fixed-size arrays of elements.
   4. Storing boolean flags.
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   Answer: B. Storing key-value pairs where keys are unique.

   A `HashMap` allows you to store data in key-value pairs. Each key must be unique, and you can use the key to retrieve its associated value.

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