Matching multiple patterns in Rust - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Rust code using multiple pattern matching?

Consider the following Rust code that uses a match statement with multiple patterns combined using the | operator. What will it print?

Rust

fn main() {
    let x = 3;
    match x {
        1 | 2 => println!("One or Two"),
        3 | 4 => println!("Three or Four"),
        _ => println!("Other"),
    }
}

A One or Two

B Other

C Three or Four

D Compilation error

💡 Hint

Look at which patterns match the value 3.

The value 3 matches the pattern '3 | 4', so the program prints 'Three or Four'.

❓ Predict Output

intermediate

What does this Rust code print when matching multiple patterns with guards?

Analyze the following Rust code that uses multiple patterns with a guard condition. What will it print?

Rust

fn main() {
    let x = 5;
    match x {
        1 | 2 | 3 if x % 2 == 0 => println!("Small even number"),
        4 | 5 | 6 => println!("Medium number"),
        _ => println!("Other"),
    }
}

A Compilation error

B Medium number

C Other

D Small even number

💡 Hint

Check which pattern matches 5 and whether the guard applies.

The value 5 matches the pattern '4 | 5 | 6' without any guard, so it prints 'Medium number'. The guard applies only to '1 | 2 | 3'.

🔧 Debug

advanced

What error does this Rust code produce when matching multiple patterns incorrectly?

This Rust code tries to match multiple patterns but has a syntax mistake. What error will the compiler show?

Rust

fn main() {
    let x = 2;
    match x {
        1 | 2 | => println!("One or Two"),
        _ => println!("Other"),
    }
}

A Error: expected pattern, found '|'

B SyntaxError: unexpected token '|'

C Error: missing comma between patterns

D No error, compiles successfully

💡 Hint

Look carefully at the pattern list and the trailing '|'.

The trailing '|' after '2' is invalid syntax. The compiler expects a pattern after '|', but finds none.

❓ Predict Output

advanced

What is the output of this Rust code using nested multiple pattern matching?

Examine the Rust code below that uses nested match with multiple patterns. What will it print?

Rust

fn main() {
    let pair = (2, 3);
    match pair {
        (1, 1) | (2, 2) => println!("Both numbers are the same and either 1 or 2"),
        (2, 3) | (3, 2) => println!("Numbers are 2 and 3 in any order"),
        _ => println!("Other pair"),
    }
}

A Both numbers are the same and either 1 or 2

B Compilation error

C Other pair

D Numbers are 2 and 3 in any order

💡 Hint

Check which pattern matches the tuple (2, 3).

The tuple (2, 3) matches the pattern '(2, 3) | (3, 2)', so it prints 'Numbers are 2 and 3 in any order'.

❓ Predict Output

expert

What is the value of variable `result` after this Rust code runs with multiple pattern matching?

Consider this Rust code that uses match with multiple patterns and returns a value. What is the final value of `result`?

Rust

fn main() {
    let ch = 'x';
    let result = match ch {
        'a' | 'e' | 'i' | 'o' | 'u' => "vowel",
        'x' | 'y' | 'z' => "special consonant",
        _ => "consonant",
    };
    println!("{}", result);
}

A "special consonant"

B "vowel"

C "consonant"

D Compilation error

💡 Hint

Check which pattern matches the character 'x'.

The character 'x' matches the pattern 'x | y | z', so `result` is set to "special consonant".