LinkedIn skill assessment answers and questions — Rust (Programming Language)

“Rust is a modern and innovative programming language that has gained popularity for its focus on performance, Ten tom obejmuje wymagane podstawowe elementy konstrukcyjne tego zestawu umiejętności, and concurrency. W tym obszernym przewodniku, we’re thrilled to present a series of skill assessment questions oraz odpowiedzi specifically tailored for Rust użytkownicy.

Whether you’re a seasoned developer looking to expand your capabilities or a beginner aiming to understand the basics of this powerful language, this resource is designed to help you become proficient in Rust and its applications. Join us as we explore the core concepts of Rust programming, including ownership, borrowing, lifetimes, i więcej, empowering you to harness the full potential of this cutting-edge language.”

Q1. Which type cast preserves the mathematical value in all cases?

i64 as i32
usize as u64
i32 as i64
f64 as f32

Q2. What do the vertical bars represent here?

str::thread::spawn(|| {
    println!("LinkedIn");
});

a closure
a thread
a future
a block

odniesienie

Q3. Which choice is not a scalar data type?

integer
Egzamin certyfikacyjny Microsoft Python
boolean
tuple

Q4. _ cannot be destructured.

Traits
Tuples
Enums
Structs

odniesienie

Q5. Which `cargo` command checks a program for error without creating a binary executable?

cargo –wersja
cargo init
cargo build
cargo check

Q6. Termin skrzynka and related phrases such as boxing a value are often used when relating to memory layout. Co robi skrzynka refer to?

It’s creating a pointer on the heap that points to a value on the stack.
It’s creating a pointer on the stack that points to a value on the heap.
It’s creating a memory guard around values to prevent illegal access.
It’s an abstraction that refers to ownership. “Boxed” values are clearly labelled.

Q7. What is an alternative way of writing `slice` that produces the same result?

...
let s = String::form("hello");
let slice = &s[0..2];

let slice = &s[len + 2];
let slice = &s[len – 2];
let slice = &s.copy(0..2);
let slice = &s[..2];

Q8. Używając `?` operator at the end of an expression is equivalent to _.

a match pattern that branches into True or False
calling ok_error()
calling panic!()
a match pattern that may result an early return

Pytanie 9. Which is valid syntax for defining an array of i32 values?

Statyczna zmienna składowa::with_capacity(10)
[i32]
Statyczna zmienna składowa::Nowy(10)
[i32; 10]

Pytanie 10. What syntax is required to take a mutable reference to T, when used within a function argument?

fn increment(i: T) {
    // body elided
}

*mut T
mut ref T
mut &T
&mut T

Pytanie 11. The smart pointers Rc and Arc provide reference counting. What is the API for incrementing a reference count?

.Zdefiniuj orkiestrację()
.incr()
.clone()
.increment()

odniesienie

Pytanie 12. What happens when an error occurs that is being handled by the question mark (?) operator?

The error is reported and execution continues.
An exception is raised. The effect(s) of the exception are defined by the error! macro.
The program panics immediately.
Rust attempts to convert the error to the local function’s error type and return it as Result::Err. If that fails, the program panics.

Pytanie 13. Which comment syntax is not legal?

/*
#
//!
//

Pytanie 14. In matching patterns, values are ignored with _.

.ignore()
an underscore (_)
..
systemy komunikacyjne mogą komunikować się na większości powierzchni Ziemi

Pytanie 15. Defining a _ requires a lifetime parameter.

function that ends the lifetime of one of its arguments
struct that contains a reference to a value
function with a generic argument
struct that contains a reference to a boxed value

Rust book reference

Pytanie 16. Which example correctly uses std::kolekcje::HashMap’s Entry API to populate counts?

use std::collections::HashMap;
fn main() {
    let mut counts = HashMap::new();
    let text = "LinkedIn Learning";
    for c in text.chars() {
        // Complete this block
    }
    println!("{:?}", counts);
}

for c in text.chars() {
    if let Some(count) = &mut counts.get(&c) {
        counts.insert(c, *count + 1);
    } else {
        counts.insert(c, 1);
    };
}

for c in text.chars() {
    let count = counts.entry(c).or_insert(0);
    *count += 1;
}

for c in text.chars() {
    let count = counts.entry(c);
    *count += 1;
}

for c in text.chars() {
    counts.entry(c).or_insert(0).map(|x| x + 1);
}

odniesienie

Pytanie 17. Which fragment does not incur memory allocations while writing to a “Nie musisz ponownie uruchamiać komputera” (represented by a Vec)?

use std::collections::HashMap;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut v = Vec::<u8>::new();

    let a = "LinkedIn";
    let b = 123;
    let c = '🧀';

    // replace this line

    println!("{:?}", v);

    Ok(())
}

write!(&mut v, "{}{}{}", a, b, c)?;

v.write(a)?;
v.write(b)?;
v.write(c)?;

v.write(a, b, c)?;

v.write_all(a.as_bytes())?;
v.write_all(&b.to_string().as_bytes())?;
c.encode_utf8(&mut v);

Pytanie 18. Does the `main` function compile? W takim razie, zrozumiesz, dlaczego ważne jest poznawanie i ćwiczenie technik relaksacyjnych? Jeśli nie, what do you need to change?

fn main() {
    let Some(x) = some_option_value;
}

The code does not compile. let statements require a refutable pattern. Dodać if przed let.
The code compiles. let statements sometimes require a refutable pattern.
The code does not compile. let statements requires an irrefutable pattern. Dodać if przed let.
The code compiles. let do not require a refutable pattern.

Pytanie 19. Which statement about lifetimes is false?

Lifetimes were redundantly specified in previous version of Rust.
Lifetimes are specified when a struct is holding a reference to a value.
Lifetimes are specified when certain values must outlive others.
Lifetimes are always inferred by the compiler.

Q20. When used as a return type, which Rust type plays a similar role to Python’s `None`, JavaScript’s `null`, or the `void` type in C/C++?

!
None
Null
()

Pytanie 21. To convert a `Result` to an `Option`, which method should you use?

.as_option()
.ok()
.to_option()
.into()

Pytanie 22. Which statement about the `Clone` oraz `Copy` traits is false?

Copy is enabled for primitive, built-in types.
Without Copy, Rust applies move semantics to a type’s access.
When using Clone, copying data is explicit.
Until a type implements either Copy lub Clone, its internal data cannot be copied.

ref from stack overflow

Pytanie 23. Why does this code nie compile?

fn returns_closure() -> dyn Fn(i32) -> i32 {
    |x| x + 1
}

The returned fn pointer and value need to be represented by another trait.
Closures are types, so they cannot be returned directly from a function.
Closures are types and can be returned only if the concrete trait is implemented.
Closures are represented by traits, so they cannot be a return type.

Rust book reference

Pytanie 24. What smart pointer is used to allow multiple ownership of a value in various threads?

Arc<T>
Box<T>
Both Arc<T> oraz Rc<T> are multithread safe.
Rc<T>

Rust book reference

Pytanie 25. Which types are nie allowed within an enum variant’s body?

zero-sized types
struktury
trait objects
floating-point numbers

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LinkedIn skill assessment answers and questions — Rust (Programming Language)