Why structs are used in Rust - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a struct named Person.

Rust

struct [1] {
    name: String,
    age: u32,
}

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

AInfo

BPerson

CData

Dperson

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase names for struct which is against Rust naming conventions.

The struct name should start with a capital letter by convention. Here, Person is the correct name.

2fill in blank

medium

Complete the code to create an instance of the struct Person.

Rust

let person = Person {
    name: String::from("Alice"),
    [1]: 30,
};

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

Ayears

Bnumber

Cage

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using a field name that does not exist in the struct.

The field for age in the struct is named age, so we must use age when creating an instance.

3fill in blank

hard

Fix the error in accessing the name field of the person instance.

Rust

println!("Name: {}", person.[1]);

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

Aname

BName

CName()

Dget_name

Attempts:

3 left

💡 Hint

Common Mistakes

Using capitalized or method-like syntax to access fields.

To access a field in a struct instance, use the exact field name in lowercase, here name.

4fill in blank

hard

Fill both blanks to define a struct and create an instance with a field value.

Rust

struct [1] {
    [2]: i32,
}

let data = [1] { value: 10 };

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

AData

Bvalue

Cnumber

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatch between struct name and instance creation.

Using wrong field names.

The struct is named Data and has a field value. The instance is created using the same struct name.

5fill in blank

hard

Fill all three blanks to create a struct, instantiate it, and access its field.

Rust

struct [1] {
    [2]: String,
}

let item = [1] { name: String::from("Book") };
println!("Item: {}", item.[2]);

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

AProduct

Bname

Ctitle

Dlabel

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for struct or fields in different places.

The struct is named Product with a field name. We create an instance and access the name field.

Practice

1. Why do Rust programmers use structs in their code?

easy

A. To group related data together under one name

B. To write faster loops

C. To create functions

D. To handle errors automatically

Solution

1. Step 1: Understand the purpose of structs

   Structs are used to combine multiple pieces of related data into one named unit.

2. Step 2: Compare with other options

   Loops, functions, and error handling are different concepts and not the main reason for structs.

3. Final Answer:

   To group related data together under one name -> Option A

4. Quick Check:

   Structs = Group related data [OK]

Hint: Structs bundle related info like a real-world object [OK]

Common Mistakes:

• Thinking structs are for loops or functions
• Confusing structs with error handling
• Believing structs speed up code automatically

2. Which of the following is the correct way to define a simple struct in Rust?

easy

A. struct Person: { name String, age u32 }

B. struct Person = (name: String, age: u32);

C. struct Person { name: String, age: u32 }

D. struct Person { name; String, age; u32 }

Solution

1. Step 1: Recall Rust struct syntax

   Rust structs use the format: struct Name { field1: Type1, field2: Type2 }.

2. Step 2: Check each option

   struct Person { name: String, age: u32 } matches the correct syntax. Options B, C, and D have syntax errors like wrong punctuation or missing colons.

3. Final Answer:

   struct Person { name: String, age: u32 } -> Option C

4. Quick Check:

   Correct struct syntax = struct Person { name: String, age: u32 } [OK]

Hint: Remember: fields use colon and commas inside braces [OK]

Common Mistakes:

• Using '=' instead of braces
• Missing colons between field names and types
• Using semicolons instead of commas

3. What will be the output of this Rust code?

struct Point { x: i32, y: i32 }

fn main() {
    let p = Point { x: 5, y: 10 };
    println!("({}, {})", p.x, p.y);
}

medium

A. Compilation error

B. (5, 10)

C. Point { x: 5, y: 10 }

D. (10, 5)

Solution

1. Step 1: Understand struct field access

   The struct Point has fields x and y. The code creates p with x=5 and y=10.

2. Step 2: Analyze the print statement

   The println! macro prints p.x and p.y in order, so output is (5, 10).

3. Final Answer:

   (5, 10) -> Option B

4. Quick Check:

   Print fields in order = (5, 10) [OK]

Hint: Print fields in order: x then y [OK]

Common Mistakes:

• Swapping x and y values
• Expecting debug print of whole struct
• Thinking code won't compile

4. Identify the error in this Rust struct usage:

struct Car {
    model: String,
    year: u32
}

fn main() {
    let my_car = Car { model: "Tesla", year: "2020" };
}

medium

A. Struct fields must be mutable

B. Missing semicolon after struct definition

C. Model field should be an integer

D. Year field has wrong type: string instead of u32

Solution

1. Step 1: Check struct field types

   The Car struct defines year as u32 (a number).

2. Step 2: Check struct initialization

   The code assigns year: "2020", which is a string, not a number. This causes a type mismatch error.

3. Final Answer:

   Year field has wrong type: string instead of u32 -> Option D

4. Quick Check:

   Field types must match exactly [OK]

Hint: Match field types exactly when creating structs [OK]

Common Mistakes:

• Using quotes around numbers
• Thinking fields must be mutable
• Missing semicolon is not the main error here

5. You want to model a Book with title, author, and number of pages using a Rust struct. Which approach best uses structs to organize this data?

hard

A. Use a struct with fields: title (String), author (String), pages (u32)

B. Use separate variables for title, author, and pages without a struct

C. Use a tuple with (String, String, u32) without naming fields

D. Use a struct with only one field holding all data as a single string

Solution

1. Step 1: Understand the goal of modeling data

   We want to group related properties of a book clearly and access them by name.

2. Step 2: Evaluate options for clarity and organization

   Use a struct with fields: title (String), author (String), pages (u32) uses a struct with named fields for each property, making code clear and organized. Use separate variables for title, author, and pages without a struct scatters data, Use a tuple with (String, String, u32) without naming fields uses unnamed tuple fields, and Use a struct with only one field holding all data as a single string mixes all data into one string, losing structure.

3. Final Answer:

   Use a struct with fields: title (String), author (String), pages (u32) -> Option A

4. Quick Check:

   Structs model real-world things with named properties [OK]

Hint: Use structs to name and group related data clearly [OK]

Common Mistakes:

• Using tuples without field names
• Storing all data in one string
• Avoiding structs and using separate variables