Formatting output in Rust - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print the value of x using Rust's formatting macro.

Rust

let x = 10;
println!("[1]", x);

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

A"{}"

B"{:?}"

C"{x}"

D"%d"

Attempts:

3 left

💡 Hint

Common Mistakes

Using %d like in C language.

Using {x} which is not valid in Rust formatting.

Using debug format {:?} when simple display is enough.

Rust uses {} inside println! to format and print values.

2fill in blank

medium

Complete the code to print the variable name with a greeting using Rust formatting.

Rust

let name = "Alice";
println!("Hello, [1]!", name);

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

A"name"

B"{:?}"

C"{}"

D"{name}"

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the variable name inside quotes, which prints the literal text.

Using debug format {:?} unnecessarily.

Trying to use {name} without the new Rust feature for named arguments.

Use {} as a placeholder to insert the value of name in the string.

3fill in blank

hard

Fix the error in the code to correctly print the floating-point number with 2 decimal places.

Rust

let pi = 3.14159;
println!("Pi is approximately [1]", pi);

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

A"{:.2f}"

B"{:.2}"

C"{:2}"

D"{:.2p}"

Attempts:

3 left

💡 Hint

Common Mistakes

Using {:.2f} which is invalid in Rust.

Using {:2} which sets width, not decimal places.

Using {:.2p} which is not a valid format specifier.

Rust uses {:.2} to format a float with 2 decimal places. The f is not used.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps words to their lengths only if length is greater than 3.

Rust

let words = ["apple", "cat", "banana", "dog"];
let lengths = words.iter().filter(|&&word| word.len() [1] 3).map(|&word| (word, word.len())).collect::<std::collections::HashMap<_, _>>();

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

A!=

B<

C==

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using < which keeps shorter words.

Using == which keeps only words of length exactly 3.

Using != which keeps all words except length 3.

The filter should keep words with length greater than 3, so use >.

5fill in blank

hard

Fill all three blanks to create a formatted string that shows the name in uppercase, age, and a check if age is over 18.

Rust

let name = "bob";
let age = 20;
let info = format!("Name: [1], Age: [2], Adult: [3]", name.[1](), age, age [3] 18);

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

Ato_uppercase

Bage

C>

Dto_lowercase

Attempts:

3 left

💡 Hint

Common Mistakes

Using to_lowercase() instead of uppercase.

Using < instead of > for age comparison.

Not calling the method with parentheses.

Use to_uppercase() to capitalize the name, print age, and check if age > 18 for adult status.