Tuple structs in Rust - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a tuple struct named Color with three u8 fields.

Rust

struct Color([1]);

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

AString

Bu8, u8, u8

Ci32

Dbool

Attempts:

3 left

💡 Hint

Common Mistakes

Using a single type instead of three types separated by commas.

Using a non-numeric type like String or bool.

The tuple struct Color has three u8 fields representing RGB values.

2fill in blank

medium

Complete the code to create an instance of the tuple struct Point with values 10 and 20.

Rust

let p = Point([1]);

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

A10, 20

BPoint(10, 20)

C(10, 20)

Dvec![10, 20]

Attempts:

3 left

💡 Hint

Common Mistakes

Using Point(10, 20) inside the parentheses again.

Using a tuple or vector syntax instead of plain values.

To create an instance of a tuple struct, provide the values inside parentheses without extra syntax.

3fill in blank

hard

Fix the error in accessing the first field of the tuple struct instance c.

Rust

let red = c.[1];

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

A0

B1

Cred

Dfirst

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to access fields by name like c.red which is invalid for tuple structs.

Using index 1 instead of 0 for the first field.

Tuple struct fields are accessed by their index starting at 0.

4fill in blank

hard

Fill both blanks to define a tuple struct Rectangle with two f64 fields and create an instance with values 5.0 and 10.0.

Rust

struct Rectangle([1]);
let rect = Rectangle([2]);

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

Af64, f64

B5.0, 10.0

Ci32, i32

D10, 5

Attempts:

3 left

💡 Hint

Common Mistakes

Using integer types i32 instead of f64.

Using integer values instead of floating point values for the instance.

The struct Rectangle has two f64 fields. The instance is created with 5.0 and 10.0.

5fill in blank

hard

Fill all three blanks to define a tuple struct Circle with a f64 radius, create an instance with radius 7.5, and access the radius field.

Rust

struct Circle([1]);
let c = Circle([2]);
let r = c.[3];

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

Af64

B7.5

C0

Dradius

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to access the field by name like c.radius which is invalid.

Using the wrong index number to access the field.

The tuple struct Circle has one f64 field. The instance is created with 7.5. The field is accessed by index 0.

Practice

1. What is a tuple struct in Rust?

easy

A. A struct with named fields accessed by name

B. A struct with unnamed fields accessed by position

C. A function that returns a tuple

D. A tuple with named elements

Solution

1. Step 1: Understand tuple struct definition

   A tuple struct groups values like a tuple but has a name for the whole struct.

2. Step 2: Identify field access method

   Fields are unnamed and accessed by position using dot and index, unlike normal structs.

3. Final Answer:

   A struct with unnamed fields accessed by position -> Option B

4. Quick Check:

   Tuple struct = unnamed fields + named struct [OK]

Hint: Tuple structs have unnamed fields accessed by dot and index [OK]

Common Mistakes:

• Confusing tuple structs with normal structs having named fields
• Thinking tuple structs are just tuples without names
• Assuming fields are accessed by name

2. Which of the following is the correct syntax to define a tuple struct named Color with three u8 fields?

easy

A. struct Color(u8, u8, u8);

B. struct Color { u8, u8, u8 }

C. struct Color(u8 u8 u8);

D. struct Color = (u8, u8, u8);

Solution

1. Step 1: Recall tuple struct syntax

   Tuple structs use parentheses with types inside, separated by commas, no field names.

2. Step 2: Check each option

   struct Color(u8, u8, u8); matches correct syntax: struct Name(Type, Type, ...); others have wrong braces, missing commas, or wrong assignment.

3. Final Answer:

   struct Color(u8, u8, u8); -> Option A

4. Quick Check:

   Tuple struct syntax = struct Name(Type, Type, ...); [OK]

Hint: Tuple structs use parentheses with types, no field names [OK]

Common Mistakes:

• Using curly braces instead of parentheses
• Omitting commas between types
• Using equals sign instead of semicolon

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

struct Point(i32, i32);
fn main() {
    let p = Point(10, 20);
    println!("{}", p.1);
}

medium

A. 20

B. Point(10, 20)

C. 10

D. Compilation error

Solution

1. Step 1: Understand tuple struct field indexing

   Fields are accessed by position starting at 0, so p.0 is 10, p.1 is 20.

2. Step 2: Identify printed value

   The code prints p.1, which is the second field, value 20.

3. Final Answer:

   20 -> Option A

4. Quick Check:

   p.1 = 20 [OK]

Hint: Tuple struct fields start at index 0, p.1 is second field [OK]

Common Mistakes:

• Confusing field index starting at 1 instead of 0
• Expecting full struct print without Debug trait
• Assuming syntax error due to dot notation

4. Identify the error in this Rust code:

struct Size(u32, u32);
fn main() {
    let s = Size { 100, 200 };
    println!("{}", s.0);
}

medium

A. Missing semicolon after struct definition

B. Accessing field with dot notation is invalid

C. Using curly braces instead of parentheses to create tuple struct instance

D. Tuple structs cannot have u32 fields

Solution

1. Step 1: Check instance creation syntax

   Tuple struct instances must be created using parentheses, e.g., Size(100, 200), not curly braces.

2. Step 2: Verify field access and other syntax

   Accessing fields with dot and index is correct; semicolon is present; u32 fields are allowed.

3. Final Answer:

   Using curly braces instead of parentheses to create tuple struct instance -> Option C

4. Quick Check:

   Tuple struct instance = parentheses, not braces [OK]

Hint: Create tuple struct instances with parentheses, not braces [OK]

Common Mistakes:

• Using braces {} instead of parentheses () for tuple struct instances
• Thinking dot notation is invalid for tuple structs
• Assuming field types are restricted

5. Given the tuple struct struct Rectangle(u32, u32);, how can you write a function area that takes a Rectangle and returns its area (width * height)?

hard

A. fn area(r: Rectangle) -> u32 { r.0 + r.1 }

B. fn area(r: Rectangle) -> u32 { r[0] * r[1] }

C. fn area(r: Rectangle) -> u32 { r.width * r.height }

D. fn area(r: Rectangle) -> u32 { r.0 * r.1 }

Solution

1. Step 1: Access tuple struct fields by index

   Tuple struct fields are accessed by dot and index, e.g., r.0 and r.1.

2. Step 2: Calculate area correctly

   Area is width times height, so multiply r.0 and r.1.

3. Final Answer:

   fn area(r: Rectangle) -> u32 { r.0 * r.1 } -> Option D

4. Quick Check:

   Use r.0 and r.1 to multiply for area [OK]

Hint: Use dot and index to access tuple struct fields for calculations [OK]

Common Mistakes:

• Using indexing syntax like r[0] which is invalid
• Trying to access fields by name when tuple struct has none
• Adding fields instead of multiplying for area