Parse integer from string in Rust

August 23, 2022  ‐ 1 min read

In some cases you may receive a numeric value as a string type, for example, a value from stdin will be given as a string. In such cases you may need to convert the string to an integer before proceeding, for this we may use the str::parse::<T>().

let input = "42";
let the_answer = input.parse::<i32>().unwrap();

If the operation fails, meaning that the string could not be parsed into the desired type, an error is thrown. Here we catch the potential error with .unwrap.

Alternatively we can specify the desired type in the assignment operation.

let input = "42";
let the_answer: i32 = input.parse().unwrap();