Rust Function: Borrow Slice, Calculate Sum

Rust Ownership, Borrowing, and Lifetimes: Exercise-7 with Solution

Write a Rust function that takes ownership of a string and returns its length.

Sample Solution:

Rust Code:

// Define a function named 'get_string_length' that takes ownership of a string and returns its length
fn get_string_length(s: String) -> usize {
    s.len() // Return the length of the string
} // Here 's' goes out of scope and is dropped. Ownership is transferred to the function when called.

fn main() {
    let my_string = String::from("Hello, world!"); // Define a string

    // Call the 'get_string_length' function and pass the ownership of 'my_string' to it
    let length = get_string_length(my_string);

    // Error! 'my_string' is no longer accessible here because ownership was transferred to the function
    // println!("Attempt to use 'my_string': {}", my_string);

    // Print the length of the string returned by the function
    println!("Length of the string: {}", length);
}

Output:

Length of the string: 13

Explanation:

Here is a brief explanation of the above Rust code:

• fn get_string_length(s: String) -> usize { ... }: This is a function named "get_string_length()" that takes ownership of a 'String' as input and returns its length as a 'usize'. The parameter 's' is of type 'String', indicating ownership transfer.
• Inside the function:
• We use the "len()" method to get the length of the string 's'.
• We return the length of the string.
• In the main function,
• Define a "String" named 'my_string'.
• We then call the "get_string_length()" function and pass the ownership of 'my_string' to it. Ownership of 'my_string' is transferred to the function, and 'my_string' goes out of scope after the function call.
• Attempting to use 'my_string' after passing ownership to the function will result in a compilation error, as ownership has been moved.
• Finally print the length of the string returned by the function.

Rust Code Editor:

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