To convert any type to a String
is as simple as implementing the ToString
trait for the type. Rather than doing so directly, you should implement the fmt::Display
trait which automagically provides ToString
and also allows printing the type as discussed in the section on print!
.
use std::fmt; struct Circle { radius: i32 } impl fmt::Display for Circle { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "Circle of radius {}", self.radius) } } fn main() { let circle = Circle { radius: 6 }; println!("{}", circle.to_string()); }
It's useful to convert strings into many types, but one of the more common string operations is to convert them from string to number. The idiomatic approach to this is to use the parse
function and either to arrange for type inference or to specify the type to parse using the ‘turbofish’ syntax. Both alternatives are shown in the following example.
This will convert the string into the type specified as long as the FromStr
trait is implemented for that type. This is implemented for numerous types within the standard library. To obtain this functionality on a user defined type simply implement the FromStr
trait for that type.
fn main() { let parsed: i32 = "5".parse().unwrap(); let turbo_parsed = "10".parse::<i32>().unwrap(); let sum = parsed + turbo_parsed; println!("Sum: {:?}", sum); }