Rust Error Handling Quick Reference Cheat Sheet
Key Takeaways
- ✓Keep this Rust Error Handling reference handy for quick syntax lookups
- ✓Focus on idiomatic Rust patterns rather than porting habits from other languages
- ✓Practice common patterns until they become muscle memory
- ✓Refer to advanced sections as specific needs arise in your projects
Rust Error Handling Essential Syntax
// Result and Option
let result: Result<i32, String> = Ok(42);
let option: Option<i32> = Some(42);
// ? operator for propagation
fn read_file(path: &str) -> Result<String, io::Error> {
let content = fs::read_to_string(path)?;
Ok(content)
}
// unwrap, expect, unwrap_or
let val = result.unwrap();
let val = result.expect("should work");
let val = result.unwrap_or(0);Rust Error Handling Common Patterns
// Pattern matching with Result
match result {
Ok(val) => println!("Success: {}", val),
Err(e) => eprintln!("Error: {}", e),
}
// if let for single pattern
if let Some(val) = optional {
println!("{}", val);
}
// Iterator chains
let sum: i32 = vec![1, 2, 3, 4, 5]
.iter()
.filter(|&&x| x > 2)
.map(|&x| x * x)
.sum();Think Your Code Is Clean? Let NexusBro QA It in 20 Seconds.
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QA My Code FreeRust Error Handling Error Handling Patterns
// Custom error type
#[derive(Debug)]
enum AppError {
NotFound(String),
Database(sqlx::Error),
Validation(String),
}
impl From<sqlx::Error> for AppError {
fn from(e: sqlx::Error) -> Self {
AppError::Database(e)
}
}
// Using thiserror crate
#[derive(thiserror::Error, Debug)]
enum AppError {
#[error("not found: {0}")]
NotFound(String),
}Rust Error Handling Type System Usage
// Generic function
fn largest<T: PartialOrd>(list: &[T]) -> &T {
let mut largest = &list[0];
for item in &list[1..] {
if item > largest { largest = item; }
}
largest
}
// Enum variants as types
enum Shape {
Circle(f64),
Rectangle(f64, f64),
}
impl Shape {
fn area(&self) -> f64 {
match self {
Shape::Circle(r) => std::f64::consts::PI * r * r,
Shape::Rectangle(w, h) => w * h,
}
}
}Rust Error Handling Testing Quick Reference
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_basic() {
assert_eq!(add(2, 3), 5);
}
#[test]
#[should_panic(expected = "overflow")]
fn test_panic() {
dangerous_operation();
}
#[test]
fn test_result() -> Result<(), String> {
let val = parse("42")?;
assert_eq!(val, 42);
Ok(())
}
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See PlansFrequently Asked Questions
How should I use this Rust Error Handling cheat sheet?
Bookmark it for quick syntax lookups during development. Focus on memorizing the essential section first. Reference specific patterns when you encounter them in code reviews or new projects. Over time, the most common patterns become second nature.
Is this Rust Error Handling cheat sheet current for 2026?
Yes. All examples use the latest stable Rust syntax and idioms. We update this reference with each major Rust release to ensure accuracy. Check the last-modified date to confirm currency.
Can I use these Rust Error Handling code snippets in production?
Yes. All snippets demonstrate idiomatic, production-quality Rust patterns. Adapt them to your specific context, add appropriate error handling, and test thoroughly before deploying. They serve as starting points, not copy-paste solutions.
What Rust version do these Rust Error Handling examples require?
Examples target the latest stable Rust version. Most work with Rust 1.70+. Specific features are noted.
Where can I practice Rust Error Handling concepts?
Use the Rust Playground (play.rust-lang.org) and rustlings exercises. Build small projects that exercise Rust Error Handling patterns. Contributing to open-source Rust projects provides real-world practice.
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