Rust Variables and Mutability

In Rust, variables are created using the let keyword. You can define a variable and assign a value to it like this:

let x = 42;

In this example, we define a variable x and assign it the value 42. Rust infers the type of x based on the value we assign to it, in this case i32.

Rust is a statically-typed language, which means that the types of variables are known at compile time. Once a variable has been defined with a certain type, it cannot be changed to a different type.

By default, variables in Rust are immutable, which means that you cannot change their value once they have been assigned. For example:

let x = 42;
x = 50; // This will produce an error

In this example, we try to assign a new value to the variable x after it has already been assigned a value. This will produce a compilation error, because x is immutable.

If you want to create a mutable variable that can be changed, you can use the mut keyword:

let mut x = 42;
x = 50; // This works

In this example, we use the mut keyword to create a mutable variable x. We can then change its value later in the code.

It's a good practice to use immutable variables whenever possible, as this can help prevent bugs and make your code more reliable. However, there are situations where mutable variables are necessary, such as when you need to update a value in a loop or in response to user input.