Match Expression

What Is a match Expression?

Match expression checks if the current value corresponds to any value within the list of values. Match expression are similar to switch statement in languages like C and C++. They give a more compact code when compared with the if/else construct.

Syntax Match expression uses a match keyword. The match expression can be written in two different ways, which are given below:
Method 1: If you do not want to assign a value to the result variable from within the match block

fn main() {
    // define a variable 
    let x = 5;
    // define match expression
    match x {
        1 => println!("Java"),
        2 => println!("Python"),
        3 => println!("C++"),
        4 => println!("C#"),
        5 => println!("Rust"),
        6 => println!("Kotlin"),
        _ => println!("Some other value"),
    };
}

output:-

Rust

Method 2:

If you want to assign a value to the result variable from within the match block

fn main(){
   // define a variable
   let course = "Rust";
   // return value of match expression in a variable
   let found_course = match course {
      "Rust" => "Rust",
      "Java" => "Java",
      "C++" => "C Plus Plus",
      "C#" => "C Sharp",
      _ => "Unknown Language"
   };
   println!("Course name : {}",found_course);
}

output:-

Course name : Rust

Quiz

Test your understanding of match expression in Rust.

What is the output of the following code?

fn main() {
  let x = 21;
 
  match x {
      1 => println!("Java"),
      2 => println!("Python"),
      3 => println!("C++"),
      4 => println!("C#"),
      5 => println!("Rust"),
      6 => println!("Kotlin"),
      _ => println!("Some other value"),
  }
}

A) Python
Java
B) Some other value

What is the output of the following code?

fn main() {
  let mut x = 2;
  match x {
      1 => println!("Java"),
      2 => println!("Python"),
      3 => println!("C++"),
      4 => println!("C#"),
      5 => println!("Rust"),
      6 => println!("Kotlin"),
      _ => println!("Some other value"),
  }
  x = 1;
  match x {
      1 => println!("Java"),
      2 => println!("Python"),
      3 => println!("C++"),
      4 => println!("C#"),
      5 => println!("Rust"),
      6 => println!("Kotlin"),
      _ => println!("Some other value"),
  }
}

A) Python
Java

B) Some other value

C) Java
Python