Convert a String to int?

Note: this question contains deprecated pre-1.0 code! The answer is correct, though.

To convert a str to an int in Rust, I can do this:

let my_int = from_str::(my_str);

The only way I know how to convert a String to an int is to get a slice of it and then use from_str on it like so:

let my_int = from_str::(my_string.as_slice());

Is there a way to directly convert a String to an int?

You can directly convert to an int using the str::parse::() method, which returns a Result containing the int.

let my_string = "27".to_string();  // `parse()` works with `&str` and `String`!
let my_int = my_string.parse::().unwrap();

You can either specify the type to parse to with the turbofish operator (::<>) as shown above or via explicit type annotation:

let my_int: i32 = my_string.parse().unwrap();

Since parse() returns a Result, it will either be an Err if the string couldn't be parsed as the type specified (for example, the string "peter" can't be parsed as i32), or an Ok with the value in it.

Stack Overflow Q#27043268, score: 743