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Tuple struct

Learn the tuple struct type and when to use it.

Tuple structs

When field names are unnecessary, a tuple struct is used; fields are accessed with .0 and .1:

struct Renk(u8, u8, u8);
struct Nokta3(i32, i32, i32);

let turuncu = Renk(255, 128, 0);
println!("{}", turuncu.0);   // 255

Even though Renk and Nokta3 have the same shape, they are different types; one can't be passed where the other is expected.

Newtype and destructuring

A single-field tuple struct is called a newtype. Its value can be unpacked with a pattern:

struct Metre(f64);
struct Saniye(f64);

fn hiz(m: Metre, s: Saniye) -> f64 {
    let Metre(yol) = m;
    yol / s.0
}

println!("{}", hiz(Metre(100.0), Saniye(8.0)));   // 12.5

Writing hiz(Saniye(8.0), Metre(100.0)) is a compile error; the mix-up in order is caught.

Practice Colour code

Define struct Renk(u8, u8, u8); and create Renk(255, 128, 0). Print the fields side by side with the {:02X} format to produce #FF8000.

Starter code

main.rs
fn main() {
    // buraya yaz
}

Sample solution

main.rs
struct Renk(u8, u8, u8);

fn main() {
    let k = Renk(255, 128, 0);
    println!("#{:02X}{:02X}{:02X}", k.0, k.1, k.2);
}

Expected output

#FF8000

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What is the "newtype" pattern for?

  • Provides inheritance
  • Separates meaning over the same base type: Metre(f64) and Saniye(f64) can't be mixed up Correct answer
  • Speeds up the program
  • Allocates memory

Explanation: A single-field tuple struct adds type safety with no runtime cost.

2 Field access

Question 
struct Renk(u8, u8, u8);
let k = Renk(10, 20, 30);
let yesil = k.____;   // 20
Answer 
struct Renk(u8, u8, u8);
let k = Renk(10, 20, 30);
let yesil = k.1;   // 20

Explanation: Tuple struct fields are numbered from 0; the second field is .1.

3 Definition and kind

Term Meaning
struct Renk(u8, u8, u8); Tuple struct
struct Metre(f64); Newtype
struct Oyuncu { ad: String } Named-field struct
let Metre(yol) = m; Unpacking with a pattern

All lessons in Beginner

1 Rust basics

  1. What is Rust?
  2. Project with Cargo
  3. Your first program
  4. println! and formatting
  5. Comments
  6. Summary - Rust basics

2 Variables

  1. Variables with let
  2. Mutability with mut
  3. Constants with const
  4. Static variables
  5. Shadowing
  6. Summary - Variables

3 Data types

  1. Integers
  2. Floating point
  3. Bool and char
  4. Tuple
  5. Array
  6. Summary - Data types

4 Strings

  1. &str vs String
  2. Creating a String
  3. Concatenating strings
  4. format! macro
  5. String length
  6. Summary - Strings

5 Project: Calculator

  1. Project skeleton
  2. Reading input
  3. Computing
  4. Error handling
  5. Loop and exit

6 Functions

  1. Defining with fn
  2. Parameters
  3. Return value
  4. Expressions and statements
  5. Early return
  6. Summary - Functions

7 Control flow

  1. if-else
  2. match basics
  3. loop
  4. while loop
  5. for loop
  6. Summary - Control flow

8 Ownership

  1. What is ownership?
  2. Move semantics
  3. Copy trait
  4. Functions and ownership
  5. Return and ownership
  6. Summary - Ownership

9 Borrowing

  1. References
  2. Mutable reference
  3. Borrowing rules
  4. Dangling reference
  5. References and functions
  6. Summary - Borrowing

10 Slices

  1. String slices
  2. Slice syntax
  3. Array slices
  4. Slices and functions
  5. Range types
  6. Summary - Slices

11 Project: Guessing game

  1. Game skeleton
  2. Reading input
  3. Comparing numbers
  4. Random number
  5. Loop and exit

12 Structs

  1. Struct definition
  2. Creating an instance
  3. Tuple struct
  4. Unit-like struct
  5. Field update
  6. Summary - Structs

13 Methods

  1. impl block
  2. self parameter
  3. &mut self
  4. Associated functions
  5. Multiple impl blocks
  6. Summary - Methods

14 Enums

  1. Enum definition
  2. Variants
  3. Variants with data
  4. Option<T>
  5. Option instead of null
  6. Summary - Enums

15 Pattern matching

  1. match patterns
  2. Value binding
  3. if let
  4. while let
  5. _ wildcard
  6. Summary - Pattern matching

16 Project: To-do CLI

  1. Task model
  2. Adding
  3. Listing
  4. Marking done
  5. Reading commands

17 Vectors

  1. Vec<T>
  2. Push and pop
  3. Index and get
  4. Looping a vector
  5. with_capacity
  6. Summary - Vectors

18 Advanced strings

  1. String and &str conversion
  2. chars and bytes
  3. Slicing strings
  4. contains and replace
  5. split and join
  6. Summary - Advanced strings

19 Error handling

  1. Result<T, E>
  2. panic!
  3. ? operator
  4. match and Result
  5. unwrap and expect
  6. Summary - Error handling

20 Beginner final

  1. Vowel counter
  2. Average calculator
  3. Bank account
  4. Temperature converter