Rust: Variables and Math

Example: A variable and output in Rust

		fn main() {
			let x = 10;
			println!("The value of x is: {}", x);
		}
	

Output:

  The value of x is: 10

Default variables are immutable, i.e. they cannot be changed. Rust does this to improve safety and concurrency.

Example: A mutable variable

		fn main() {
			let mut x = 10;
			println!("The value of x is: {}", x);
			x = 15;
			println!("The value of x is: {}", x);
		}
	

Output:

  The value of x is: 10   The value of x is: 15

Immutable variables are like constants - that are values bound to a name and are not allowed to change. However, there are a few differences between constants and variables. You can't use mut with constants - constants are always immutable. Constrants are declared using the const keyword instead of let. THe type of the value for a constant must be annotated. Constants may also only be set to a constant expression and not the result of a function call or any other value that could only be computed at runtime.