Rust for beginners — Part 8 — &str

Let’s look into how we can utilize strings in rust using &str type.

Note: Kindly have a look into the previous section of tutorial to understand about borrowing reference, mutable borrow and immutable borrow in rust

Previous section: https://medium.com/@manikandan96372/rust-for-beginners-part-7-borrowing-reference-mutable-borrow-immutable-borrow-5c0e5c84e1ef

&str is another type of string in rust that is used to view the data that are stored as string.

fn main() {
  let a: &str = "hello";
  println!("{}", a);
}

The above code snippet on execution would give the following output

hello

looks good, now let’s try to mutate the variable a by re-assigning a different value to it after its initialization

fn main() {
let a: &str = "hello";
a = "world";
println!("{}", a);
}

The above code snippet on execution would give the following error

The above error clearly states that variable with type &str are

1. Immutable, it cannot be mutated once it is defined, so it can only be read once it is defined
2. The basic difference between String and &str type is that String can be mutated because it has the ownership of that variable but where as &str can only be used to read the variable but cannot own it.
3. Re-assigning or any method to mutate it like “push_str” are not allowed with &str type.
4. Variables with &str type has a fixed size in the memory and have no chance to be modified in future.

Now we understood how &str type is used in rust, let’s look into struct in the next section