Result Handling
Level: intro (score: 1)
🚀 These intro exercises are prep for our
Rust Intro Cohort Program.
🎯 Python has try/except, but Rust takes a different path with Result.
Instead of throwing exceptions, Rust encourages you to return a Result<T, E> where:
- T is the type you return on success (Ok)
- E is the type you return on failure (Err)
This forces you to explicitly handle success and failure cases, making your code safer and more predictable.
✅ Your task:
Implement the divide function which:
- Takes two integers
aandb - Returns
Ok(a / b)ifbis not zero - Returns an
Err(String)with the message"division by zero"ifbis zero
This exercise introduces:
- The Result enum (Ok and Err variants)
- Using generics in Result<T, E>
- Defensive programming in Rust
🧠 Remember: in Rust, not handling an error is a compile-time error — it’s part of the language’s safety guarantees.
pub fn divide(a: i32, b: i32) -> Result<i32, String> {
// your code here
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_divide_normal() {
assert_eq!(divide(10, 2), Ok(5));
assert_eq!(divide(7, 2), Ok(3));
}
#[test]
fn test_divide_zero() {
assert_eq!(divide(10, 0), Err("division by zero".to_string()));
assert_eq!(divide(-5, 0), Err("division by zero".to_string()));
}
}