Converting a String to int in Rust

Alex Garella

8th September 2023

Data conversions are an integral part of programming. If you're wondering how to convert a String to an int in Rust, you're in the right place.

Using the parse Method

Rust provides the parse() method, which tries to convert a String to a specified data type.

fn main() { let s: String = "42".to_string(); let number: i32 = s.parse().expect("Not a valid number"); println!("{}", number); // Outputs: 42 }

Note: We've used expect() for simplicity, but in real-world code, you'd handle the Result more gracefully.

Error Handling with parse

The parse() method returns a Result, which can be an Ok(T) or an Err. To handle potential errors:

fn main() { let s = "42a".to_string(); match s.parse::<i32>() { Ok(n) => println!("Number: {}", n), Err(e) => println!("Error: {}", e), } } // Outputs: Error: invalid digit found in string


Converting a String to an int in Rust is straightforward using the parse() method. By leveraging Rust's powerful error handling mechanism, you ensure safe and predictable conversions.

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