Rust Lifetimes Quiz

0 Passed

0% acceptance

40 in-depth questions covering Rust's lifetime system, lifetime annotations, elision rules, function signatures with lifetimes, struct references, and common lifetime errors — with 11 code examples to solidify understanding.

40 Questions

~80 minutes

Question 1

What are lifetimes in Rust?

How long a program runs

The scope for which a reference is valid

Memory allocation duration

Variable declaration time

Question 2

What is the syntax for lifetime annotations?

'a'

Question 3

When does Rust require explicit lifetime annotations?

Always

Never

When the compiler cannot infer lifetimes automatically

Only for structs

Question 4

What are the lifetime elision rules?

Rules that allow omitting lifetime annotations in function signatures

Rules for extending variable lifetimes

Rules for garbage collection

Rules for memory allocation

Question 5

What is the first lifetime elision rule?

Each parameter gets its own lifetime

All parameters get the same lifetime

Return value gets a new lifetime

No elision for return values

Question 6

What is the second lifetime elision rule?

If there's exactly one input lifetime, it's assigned to all output lifetimes

Each output gets its own lifetime

Outputs cannot have lifetimes

Only one output lifetime allowed

Question 7

What is the third lifetime elision rule?

Methods get &self lifetimes

If there are multiple input lifetimes, one is &self, outputs get &self lifetime

Methods cannot elide lifetimes

Methods always need explicit lifetimes

Question 8

What will this function signature elide to?

rust

fn first_word(s: &str) -> &str

fn first_word<'a>(s: &'a str) -> &'a str

fn first_word<'a>(s: &str) -> &'a str

fn first_word(s: &str) -> &str

Compilation error

Question 9

What will this function signature elide to?

rust

fn longest(x: &str, y: &str) -> &str

fn longest<'a>(x: &'a str, y: &'a str) -> &'a str

fn longest<'a, 'b>(x: &'a str, y: &'b str) -> &'a str

Compilation error

No elision possible

Question 10

What will this method signature elide to?

rust

fn get_name(&self) -> &str

fn get_name<'a>(&'a self) -> &'a str

fn get_name(&self) -> &str

Compilation error

fn get_name<'a>(&self) -> &'a str

Question 11

What is a lifetime parameter in a function?

A parameter that specifies how long the function runs

A generic parameter that constrains reference lifetimes

A parameter for memory allocation

A parameter for function timeout

Question 12

What does this function signature mean?

rust

fn longest<'a>(x: &'a str, y: &'a str) -> &'a str

x and y have different lifetimes

x and y have the same lifetime, return has that lifetime

The return has a different lifetime

No lifetime constraints

Question 13

What will this code do?

rust

fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
    if x.len() > y.len() { x } else { y }
}

fn main() {
    let s1 = String::from("short");
    let result;
    {
        let s2 = String::from("longer");
        result = longest(&s1, &s2);
    }
    println!("{}", result);
}

Print 'longer'

Compilation error

Print 'short'

Runtime panic

Question 14

How can you fix the lifetime error in the previous question?

Use different lifetime parameters

Move the println! inside the block

Use Rc<T>

Remove the lifetime annotation

Question 15

What is a struct with lifetime parameters?

A struct that lives for a specific time

A struct containing references with lifetime constraints

A struct with timing methods

A struct for measuring performance

Question 16

What is the correct syntax for a struct with lifetimes?

struct Foo<'a> { field: &'a str }

struct Foo { field: &'a str }

struct Foo<'a> { field: &str }

struct Foo { field: &str }

Question 17

What will this code do?

rust

struct Book<'a> {
    title: &'a str,
}

fn main() {
    let book;
    {
        let title = String::from("1984");
        book = Book { title: &title };
    }
    println!("{}", book.title);
}

Print '1984'

Compilation error

Runtime panic

Print garbage

Question 18

What is a common lifetime error message?

'a does not live long enough

Expected &str, found String

Cannot move out of borrowed content

Mismatched types

Question 19

What does 'borrowed value does not live long enough' mean?

The value is deallocated too early

The value lives too long

The value is copied

The value is moved

Question 20

What is the 'static lifetime?

The lifetime of the program

A very short lifetime

The lifetime of a function

The lifetime of a loop

Question 21

When can you use 'static lifetime?

For all references

For string literals and static variables

For local variables

Never

Question 22

What will this code do?

rust

fn get_static() -> &'static str {
    "hello"
}

fn main() {
    let s = get_static();
    println!("{}", s);
}

Print 'hello'

Compilation error

Runtime panic

Print nothing

Question 23

What is lifetime subtyping?

One lifetime being shorter than another

Lifetimes being equal

Lifetimes being longer

Lifetime conversion

Question 24

What does this syntax mean?

rust

fn foo<'a, 'b: 'a>(x: &'a str, y: &'b str) -> &'a str

'a is shorter than 'b

'b outlives 'a

'a and 'b are equal

'a outlives 'b

Question 25

What is the T: 'a syntax?

T lives longer than 'a

Any references in T must outlive 'a

T has lifetime 'a

T is borrowed for 'a

Question 26

What will this code do?

rust

fn longest<'a>(x: &'a str, y: &str) -> &'a str {
    x
}

fn main() {
    let s1 = String::from("short");
    let result;
    {
        let s2 = String::from("long");
        result = longest(&s1, &s2);
    }
    println!("{}", result);
}

Print 'short'

Compilation error

Runtime panic

Print 'long'

Question 27

What is the difference between lifetime annotations and generic type parameters?

No difference

Lifetimes constrain references, generics constrain types

Lifetimes are for types, generics for references

Lifetimes replace generics

Question 28

What is a lifetime in a trait bound?

How long the trait is valid

Constraining associated types or references in traits

Trait method duration

Trait implementation time

Question 29

What will this code do?

rust

struct Ref<'a, T> {
    value: &'a T,
}

fn main() {
    let x = 5;
    let r = Ref { value: &x };
    println!("{}", r.value);
}

Print 5

Compilation error

Runtime panic

Print 0

Question 30

What is the HRTB (Higher-Ranked Trait Bounds) syntax?

for<'a> syntax for higher-ranked lifetimes

A way to specify longer lifetimes

A replacement for lifetime annotations

A way to avoid lifetimes

Question 31

When would you use HRTB?

For closures that return references

For simple function signatures

For struct definitions

Never

Question 32

What is a common source of lifetime errors in Rust?

Using the wrong variable names

Trying to return references to local variables

Using the wrong data types

Incorrect indentation

Question 33

How can you fix 'does not live long enough' errors?

Always use 'static

Restructure code to match lifetimes or return owned values

Use unsafe code

Ignore the error

Question 34

What is lifetime variance?

How lifetimes change in subtyping

Lifetime performance

Lifetime syntax

Lifetime conversion

Question 35

What is covariance in lifetimes?

Shorter lifetimes can be used as longer ones

Longer lifetimes can be used as shorter ones

Lifetimes cannot be converted

All lifetimes are equal

Question 36

What is contravariance in lifetimes?

Function that takes &'long T can accept &'short T

Function that takes &'short T can accept &'long T

Lifetimes are invariant

No contravariance in Rust

Question 37

What does invariant mean for lifetimes?

Lifetimes can be converted freely

Lifetimes cannot be converted

Lifetimes are covariant

Lifetimes are contravariant

Question 38

When are mutable references invariant?

Always

For safety reasons

For performance

Never

Question 39

What is the 'outlives' relationship?

'a: 'b means 'a lives longer than 'b

'a: 'b means 'b lives longer than 'a

'a: 'b means they are equal

'a: 'b is invalid syntax

Question 40

What is the most challenging aspect of learning lifetimes?

The syntax

Thinking about reference validity and relationships

Performance implications

Integration with borrowing

Other Quiz Categories

JavaScript

47 quizzes

Basics

Variables & Data Types

Operators & Expressions

Python

29 quizzes

Introduction & Core Fundamentals

Data Types & Zero Values

Operators & Expressions

C++

26 quizzes

Basics

Variables & Data Types

Operators & Expression

Java

22 quizzes

Java Basics & JVM Fundamentals

Variables, Data Types & Type Casting

Operators & Expressions

Matlab

21 quizzes

Basics & Environment

Variables and Data Type

Arrays and Matric

TypeScript

19 quizzes

Introduction and Overview

Installation and Configuration

Basic Types and Type Annotations

SQL Database

15 quizzes

Foundations and Basics

Basic Query Selection

Filter, Sort, and Alias Essentials

PHP

15 quizzes

Syntax Building Blocks

Node Structure and Pointer Fundamentals

Singly Linked List

QUIZZES IN Rust

Cargo and Project Setup

40 comprehensive questions on Rust's package manager Cargo, covering project initialization, building, running, project structure, and dependency management — with 15 code examples demonstrating practical Cargo usage.

Variables and Mutability

40 comprehensive questions on Rust's variable system, covering let bindings, mut keyword, shadowing, type inference, and constants — with 12 code examples demonstrating practical variable usage patterns.

Data Types

45 comprehensive questions on Rust's type system, covering scalar types, compound types, type conversions, numeric operations, and string types — with 15 code examples demonstrating practical type usage patterns.

Control Flow

45 comprehensive questions on Rust's control flow constructs, covering if expressions, loops, and control flow keywords — with 15 code examples demonstrating practical control flow usage.

Functions

40 questions covering function parameters, return values, expressions, diverging functions, and function scope in Rust.

Ownership

45 in-depth questions covering Rust's ownership system, move semantics, copy types, resource cleanup through Drop trait, precise drop timing, and ownership transfer patterns — with 12 code examples to solidify understanding.

Borrowing

45 in-depth questions covering Rust's borrowing system, immutable and mutable references, aliasing rules, reference scopes, and borrow checker validation — with 13 code examples to solidify understanding.

Lifetimes

Strings

40 comprehensive questions on Rust's string types, covering String vs &str, UTF-8 behavior, slicing, mutating strings, and conversions — with 11 code examples demonstrating practical string handling patterns.

Collections

40 comprehensive questions on Rust's collection types, covering Vec, HashMap, VecDeque, iteration patterns, and capacity management — with 11 code examples demonstrating practical collection usage.

Slices

40 comprehensive questions on Rust's slice types, covering borrowed views, indexing, mutable slices, ranges, and slice methods — with 11 code examples demonstrating practical slice usage patterns.

Pattern Matching

40 comprehensive questions on Rust's pattern matching system, covering match expressions, destructuring, guards, wildcards, and enum matching — with 11 code examples demonstrating practical pattern matching techniques.

Enums

40 comprehensive questions on Rust's enum system, covering simple variants, data-carrying variants, enum matching, methods on enums, and Option/Result patterns — with 11 code examples demonstrating practical enum usage.

Struct

40 comprehensive questions on Rust's struct system, covering named fields, tuple structs, methods, associated functions, and field ownership — with 11 code examples demonstrating practical struct usage.

Modules

40 comprehensive questions on Rust's module system, covering module creation, visibility, imports, paths, and the use keyword — with 11 code examples demonstrating practical module organization patterns.

Traits

40 comprehensive questions on Rust's trait system, covering trait definitions, implementations, bounds, associated types, and trait objects — with 11 code examples demonstrating practical trait usage patterns.

Generic

40 comprehensive questions on Rust's generic programming system, covering generic functions, structs, enums, impl blocks, and monomorphization — with 11 code examples demonstrating practical generic usage patterns.

Iterators

Master Rust's powerful iterator system for efficient data processing and transformation

Closures

Master Rust's closure system for capturing environment variables and creating flexible function-like constructs

Error Handling

Master Rust's robust error handling system with Result, Option, and the ? operator for reliable code

File and I/O Operations

Master Rust's file system operations and I/O handling for robust data persistence and streaming

Smart Pointers

Master Rust's smart pointer types for automatic memory management and safe heap allocation

Concurrency

Master Rust's concurrency model with threads, channels, and synchronization primitives for safe parallel programming

Async Programming

Master asynchronous programming in Rust with futures, async/await, and concurrent execution patterns

Memory Management

Deep dive into Rust's ownership system, borrowing rules, and advanced memory management patterns for safe and efficient code

Macros

Master Rust's metaprogramming system with declarative and procedural macros for code generation and compile-time programming

Attributes

Master Rust's attribute system for conditional compilation, testing, documentation, and code generation

Testing

Master comprehensive testing strategies in Rust including unit tests, integration tests, documentation tests, and testing best practices

Crate Architecture

Master the design and organization of Rust crates including module systems, workspace management, dependency handling, and publishing strategies

Performance and Optimization

Master advanced performance techniques in Rust including profiling, benchmarking, memory optimization, and compiler optimizations

Rust Lifetimes Quiz

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

Question 21

Question 22

Question 23

Question 24

Question 25

Question 26

Question 27

Question 28

Question 29

Question 30

Question 31

Question 32

Question 33

Question 34

Question 35

Question 36

Question 37

Question 38

Question 39

Question 40

About This Rust Lifetimes Quiz

What You Will Practise

Other Quiz Categories

QUIZZES IN Rust

Cargo and Project Setup

Variables and Mutability

Data Types

Control Flow

Functions

Ownership

Borrowing

Lifetimes

Strings

Collections

Slices

Pattern Matching

Enums

Struct

Modules

Traits

Generic

Iterators

Closures

Error Handling

File and I/O Operations

Smart Pointers

Concurrency

Async Programming

Memory Management

Macros

Attributes

Testing

Crate Architecture

Performance and Optimization