rustLogic errorEasy

Unnecessary string clone when borrowing suffices

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What it should do

Calculate length of string without unnecessary cloning. Example: calculate_string_length("hello") -> 5

What happens instead

Performance warning: unnecessary deep clone of String just to measure length

fn calculate_string_length(s: &str) -> usize {
    // Unnecessary .to_string().clone() allocates heap memory just for length
    let owned = s.to_string();
    let cloned = owned.clone();
    cloned.len()
}

fn main() {
    println!("{}", calculate_string_length("hello"));
}

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

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This bug belongs to the logic errors pattern

The wrong operator, an inverted condition, a formula the right way round but backwards.

Learn the logic errors pattern Step through your own code

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fn calculate_string_length(s: &str) -> usize { // Unnecessary .to_string().clone() allocates heap memory just for length let owned = s.to_string(); let cloned = owned.clone(); cloned.len() } fn main() { println!("{}", calculate_string_length("hello")); }

Unnecessary string clone when borrowing suffices

What it should do

What happens instead

More logic errors to practise

Unnecessary string clone when borrowing suffices

What it should do

What happens instead

More logic errors to practise