Rust Function: Length of option string handling

Last update on December 21 2024 10:22:33 (UTC/GMT +8 hours)

Write a Rust function that takes an Option<&str> and returns the length of the string if it's Some(&str) and 0 if it's None.

Sample Solution:

Rust Code:

// Function that takes an Option<&str> and returns the length of the string if it's Some(&str)
// and 0 if it's None.
fn length_of_string(option_str: Option<&str>) -> usize {
    // Use match to pattern match the Option
    match option_str {
        // If it's Some(&str), return the length of the string
        Some(s) => s.len(),
        // If it's None, return 0
        None => 0,
    }
}

fn main() {
    // Example usage
    let some_str = Some("Rust Exercises!"); // Option containing a string
    let none_str: Option<&str> = None; // None
    
    // Print the length of the string if it's Some(&str) or 0 if it's None
    println!("{}", length_of_string(some_str)); // Output: 4
    println!("{}", length_of_string(none_str)); // Output: 0
}

Output:

15
0

Explanation:

In the exercise above,

• The "length_of_string()" function takes an Option<&str> as input and returns a 'usize'.
• Inside the function, a 'match' expression is used to pattern match the 'Option'.
• If the 'Option' is 'Some(&str)', the length of the string is returned using the "len()" method.
• If the 'Option' is 'None', 0 is returned.

Rust Code Editor:

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