Reading input basics in Rust - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read a line of input from the user.

Rust

use std::io;

fn main() {
    let mut input = String::new();
    io::stdin().[1](&mut input).expect("Failed to read line");
    println!("You typed: {}", input);
}

Drag options to blanks, or click blank then click option'

Aread_exact

Bread_to_string

Cread_line

Dread

Attempts:

3 left

💡 Hint

Common Mistakes

Using read_to_string which reads until EOF, not just one line.

Using read_exact which requires a fixed number of bytes.

The read_line method reads a line from standard input into the given string buffer.

2fill in blank

medium

Complete the code to trim whitespace from the input string.

Rust

use std::io;

fn main() {
    let mut input = String::new();
    io::stdin().read_line(&mut input).expect("Failed to read line");
    let trimmed = input.[1]();
    println!("Trimmed input: {}", trimmed);
}

Drag options to blanks, or click blank then click option'

Atrim

Btrim_start

Ctrim_end

Dstrip

Attempts:

3 left

💡 Hint

Common Mistakes

Using trim_start or trim_end which only remove whitespace from one side.

Using strip which does not exist in Rust String.

The trim method removes whitespace from both ends of a string.

3fill in blank

hard

Fix the error in the code to parse the input string into an integer.

Rust

use std::io;

fn main() {
    let mut input = String::new();
    io::stdin().read_line(&mut input).expect("Failed to read line");
    let num: i32 = input.[1]().parse().expect("Not a number");
    println!("Number is: {}", num);
}

Drag options to blanks, or click blank then click option'

Aclone

Bto_string

Cparse

Dtrim

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to parse the raw input string with newline, causing parse error.

Using to_string or clone which do not remove whitespace.

We use trim to remove newline and spaces before parsing the string to an integer.

4fill in blank

hard

Fill both blanks to create a dictionary (HashMap) from words to their lengths, filtering words longer than 3 characters.

Rust

use std::collections::HashMap;

fn main() {
    let words = vec!["apple", "cat", "banana", "dog"];
    let lengths: HashMap<_, _> = words.iter().map(|word| (word, word.len())).filter(|(_, &len)| len [1] 3).collect();
    println!("{:?}", lengths);
}

Drag options to blanks, or click blank then click option'

A<

B>

C>=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' or '<=' which filters shorter words.

Using '>=' which includes words of length 3.

The filter keeps words whose length is greater than 3.

5fill in blank

hard

Fill all three blanks to read input, trim it, parse to i32, and print the number.

Rust

use std::io;

fn main() {
    let mut input = String::new();
    io::stdin().[1](&mut input).expect("Failed to read line");
    let num: i32 = input.[2]().parse().expect("Not a number");
    println!("You entered: {}", [3]);
}

Drag options to blanks, or click blank then click option'

Aread_line

Btrim

Cnum

Dparse

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to trim before parsing causing errors.

Printing the input string instead of the parsed number.

First, read a line with read_line. Then trim whitespace with trim. Finally, print the parsed number variable num.