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Puzzle 4: Explanation

Explore how Rust manages integer overflow through debug and release modes by using two’s complement representation. Learn about Rust’s overflow checks, safe wrapping behaviors, and functions like checked_add that help detect and handle overflow to write safer code.

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Test it out

Hit “Run” to see the code’s output. The answer depends on how we run the program.

Running in debug mode

If we run the program in debug mode with cargo run, the program will display a series of numbers from 0 to 127 and then crash while displaying the following error message:

thread 'main' panicked at 'attempt to add with overflow', main.rs:5:7.
C++
fn main() {
  let mut counter : i8 = 0; 
  loop {
    println!("{}", counter);
      counter += 1;
  }
}

Run the program in release mode

If we run the program in release mode with cargo run --release, the program will display a series of numbers from 0 to 127 and then ...