Rust: Defining Variables

Variables

In Rust, variables are defined using the let keyword.

let team_name = "Rustaceans";

By default, Rust variables are immutable.

Once defined, its value can't be changed.

let team_name = "Rustaceans";

team_name = "Crustaceans"; // This raises an error!

Mutability

The mut keyword can be used to define a variable that can change, i.e. a "mutable" variable.

let team_name = "Rustaceans";
team_name = "Crustaceans"; // This raises an error!

let mut mutable_team_name = "Rustaceans";
mutable_team_name = "Crustaceans"; // This doesn't error

Summary

In this concept, we learned about the following:

• Variables: The let keyword is used to define variables. Variables are immutable by default.

• Mutability: The mut keyword is used to make variables mutable.

You can learn more about this in the Variables and Mutability chapter of the Rust book.