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String slice panics on non-UTF-8 char boundary

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BugFind the bug and fix the code

What it should do

Extract a substring from a given string based on start and end indices. Example: extract_utf8_substring(s, start, end) -> substring

What happens instead

thread 'main' panicked at 'byte index 3 is not on a char boundary', src/main.rs:6:10

fn extract_utf8_substring(s: &str, start: usize, end: usize) -> &str {
    &s[start..end]
}

fn main() {
    let s = " café";
    let result = extract_utf8_substring(s, 1, 3);
    println!("{}", result);
}

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 mutation and copying bugs pattern

Assignment does not copy, a shallow copy still shares its contents, and mutating methods return None.

Learn the mutation and copying bugs pattern Step through your own code

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fn extract_utf8_substring(s: &str, start: usize, end: usize) -> &str { &s[start..end] } fn main() { let s = " café"; let result = extract_utf8_substring(s, 1, 3); println!("{}", result); }

String slice panics on non-UTF-8 char boundary

What it should do

What happens instead

More mutation and copying bugs to practise

String slice panics on non-UTF-8 char boundary

What it should do

What happens instead

More mutation and copying bugs to practise