EN
RU
ES
ZH
FR
DE
PT
AR
HI
Introduction: Why Does Rust Seem Difficult?
Rust is a modern systems programming language that guarantees memory safety without a garbage collector. However, its strict type system and unique ownership model often confuse beginners. If you are just starting to learn Rust and constantly see red messages from the compiler, do not despair — this is normal. In this article, we will break down the 10 most common mistakes of beginner Rust developers and show how to fix them.
1. Ignoring the borrow checker
The most popular mistake is trying to use a value after a move or creating a mutable reference. The Rust compiler (borrow checker) strictly enforces ownership rules.
Problem
let s1 = String::from("hello");let s2 = s1; // s1 moved to s2println!("{}", s1); // Error! s1 no longer owns the dataSolution
Use clone() if you need to copy data, or pass references &:
let s1 = String::from("hello");let s2 = &s1; // borrowingprintln!("{} and {}", s1, s2); // Works!Tip: If the compiler complains about ownership — you most likely need a reference, not a full move.
2. Confusion between String and &str
Beginners often do not understand the difference between the owning type String and the slice &str. This leads to type errors and unnecessary allocations.
Problem
fn greet(name: &str) { println!("Hello, {}!", name);}
let my_name = String::from("Anna");greet(my_name); // Error: expected &str, found StringSolution
Pass a reference to String — it will automatically coerce to &str:
greet(&my_name); // Works thanks to Deref coercionUse String for owning and modifying strings, and &str for reading and passing to functions.
3. Overusing unwrap() and expect()
The methods unwrap() and expect() are a quick way to handle Option or Result, but they cause a panic on error. This is unacceptable in production code.
Problem
let number: Option<i32> = None;let value = number.unwrap(); // Panic!Solution
Use match or the methods unwrap_or, unwrap_or_else:
let value = number.unwrap_or(0); // Returns 0 if None// Or with matchmatch number { Some(v) => println!("{}", v), None => println!("Value is absent"),}For Result, use the ? operator to propagate the error upwards.
4. Incorrect use of mutable references
The rule "one mutable reference OR multiple immutable references" is constantly violated.
Problem
let mut data = vec![1, 2, 3];let ref1 = &mut data;let ref2 = &mut data; // Error!println!("{}", ref1);Solution
Limit the scope of mutable references using curly braces:
let mut data = vec![1, 2, 3];{ let ref1 = &mut data; ref1.push(4);} // ref1 goes out of scopelet ref2 = &mut data; // Now it's possibleref2.push(5);5. Forgotten lifetimes
When the compiler requires explicitly specifying a lifetime, beginners get stuck. The most common mistake is returning a reference to a local variable.
Problem
fn get_ref() -> &str { let s = String::from("test"); &s // Error: returning a reference to a local variable}Solution
Either return the owning type String, or accept a reference as an argument:
Blogs
Book Recommendations
Read also
