const)Welcome to our deep dive into Rust's world of constants! In this lesson, we'll learn about const in Rust, a powerful tool to define and use constants in your projects.
Let's start with the basics 🎯:
Just like in other programming languages, constants in Rust are immutable values that we can use throughout our code. Constants are declared with the const keyword followed by a name and an initial value.
Here's a simple example:
const MY_FAVORITE_COLOR: &str = "Blue";In this example, MY_FAVORITE_COLOR is a constant with the value "Blue". 💡 Pro Tip: Constants are always implicitly marked as immutable in Rust, meaning they cannot be reassigned once defined.
Like variables, constants also have types in Rust. The type of a constant is inferred based on the initial value you provide.
For instance, let's create a constant PI with a floating-point value:
const PI: f64 = 3.14159265358979323846;Here, the type of the constant PI is f64, a floating-point number with 6 decimal places of precision.
Using constants in Rust is quite straightforward. You can access a constant like any other variable in your code:
fn main() {
println!("My favorite color is: {}", MY_FAVORITE_COLOR);
println!("PI value is: {}", PI);
}When you run this code, you'll see the output as:
My favorite color is: Blue
PI value is: 3.141593
Now, let's test your understanding with a quiz 📝:
What's the type of the constant `PI` in the following code?
Stay tuned for our next lesson, where we'll delve deeper into constants in Rust, exploring advanced usage and best practices! ✅