When should I use panic vs Result

Use panic! for unrecoverable errors where continuing execution is impossible or unsafe, and use Result for recoverable errors where the program can handle the failure and continue.

// Use panic! for logic errors or impossible states
if value < 1 || value > 100 {
    panic!("Guess value must be between 1 and 100, got {value}.");
}

// Use Result for expected failures like file I/O
let file = std::fs::File::open("hello.txt")
    .expect("hello.txt should be included in this project");

Use panic! when something goes wrong that you cannot fix, like a logic error, so the program stops immediately to prevent bad data. Use Result when an error is expected and manageable, like a missing file, so the program can try a backup plan or tell the user nicely. Think of panic! as pulling the emergency brake and Result as a detour sign.