The simplest form of type conversion is a type cast expression. It is denoted with the binary operator as. For instance, println!("{}", 1 + 1.0); would not compile, since 1 is an integer while 1.0 is a float. However, println!("{}", 1 as f32 + 1.0) should compile. The exercise conversions1 tries to cover this.

Rust also offers traits that facilitate type conversions upon implementation. These traits can be found under the convert module. The traits are the following:

From and Into covered in conversions2
TryFrom and TryInto covered in conversions4
AsRef and AsMut covered in conversions5

AsRef and AsMut are useful when a function only needs to borrow a value in another form. For example, a function accepting T: AsRef<str> can work with both a string slice and an owned String without requiring separate implementations for each type.

Furthermore, the std::str module offers a trait called FromStr which helps with converting strings into target types via the parse method on strings. If properly implemented for a given type Person, then let p: Person = "Mark,20".parse().unwrap() should both compile and run without panicking.

These should be the main ways within the standard library to convert data into your desired types.

Further information

These are not directly covered in the book, but the standard library has a great documentation for it.