rustLogic errorMedium

Uninitialized memory access in array processing

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What it should do

Process an array of MaybeUninit elements and return a Vec<i32>. Example: process_array([MaybeUninit::uninit(); 5]) -> Vec<i32>

What happens instead

Program panics with 'attempt to read from uninitialized memory' at runtime

use std::mem::MaybeUninit;

fn process_array(arr: [MaybeUninit<i32>; 5]) -> Vec<i32> {
    let mut result = Vec::new();
    for elem in arr {
        result.push(unsafe { elem.assume_init() });
    }
    result
}

fn main() {
    let arr = [MaybeUninit::uninit(); 5];
    let result = process_array(arr);
    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 logic errors pattern

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

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use std::mem::MaybeUninit; fn process_array(arr: [MaybeUninit<i32>; 5]) -> Vec<i32> { let mut result = Vec::new(); for elem in arr { result.push(unsafe { elem.assume_init() }); } result } fn main() { let arr = [MaybeUninit::uninit(); 5]; let result = process_array(arr); println!("{:?}", result); }

Uninitialized memory access in array processing

What it should do

What happens instead

More logic errors to practise

Uninitialized memory access in array processing

What it should do

What happens instead

More logic errors to practise