rustNull / UndefinedMedium

Unexpected runtime panic during file processing

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BugFind the bug and fix the code

What it should do

Read a file and return its contents as a String. Example: process_file_contents("example.txt") -> "file contents"

What happens instead

thread 'main' panicked at 'called `Option::unwrap()` on a `None` value'

use std::fs::File; use std::io::Read;

fn process_file_contents(filename: &str) -> String {
    let mut file = File::open(filename).unwrap();
    let mut contents = String::new();
    file.read_to_string(&mut contents).unwrap();
    contents
}

fn main() {
    let contents = process_file_contents("non_existent_file.txt");
    println!("File contents: {}", contents);
}

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 null and undefined errors pattern

Cannot read properties of undefined, NoneType has no attribute, NaN appearing from nowhere.

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use std::fs::File; use std::io::Read; fn process_file_contents(filename: &str) -> String { let mut file = File::open(filename).unwrap(); let mut contents = String::new(); file.read_to_string(&mut contents).unwrap(); contents } fn main() { let contents = process_file_contents("non_existent_file.txt"); println!("File contents: {}", contents); }

Unexpected runtime panic during file processing

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Unexpected runtime panic during file processing

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