rustlings

Intro

• Rust uses the print! and println! macros to print text to the console.
• Positional arguments can be used println!("Hello {}!", "world");.

Variables

In Rust, variables are immutable by default. When a variable is immutable, once a value is bound to a name, you can’t change that value. You can make them mutable by adding mut in front of the variable name.

• Declare a variable using let
• A variable should be given an explicit type and a value. let x: i32 = 0;
• Shadowing: you can declare a new variable with the same name as a previous variable. https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#shadowing
• Constants const NUMBER: i32 = 3;

Functions

• Rust requires that all parts of a function's signature have type annotations.
• After the ->. This is where the function's return type should be.
• Rust distinguishes between expressions and statements: expressions return a value based on their operand(s), and statements simply return a () type which behaves just like void in C/C++ language. To return the value, use return or remove the semicolon at the end.
• How Functions Work

If statement (control flow)

• if condition does not need to be surrounded by parentheses.
• Each condition is followed by a {} block.
• Multiple conditions: if condition {} else if condition2 {} else {}.
• In Rust, every arm of an if expression has to return the same type of value.

Primitive types

• Boolean bool
• Characters char: note the single quotes let character = '/'.
• Arrays let _: [u8; 3] = [1, 2, 3]; or let _: [u8; 3] = [0; 3];
• Tuple let cat = ("Furry McFurson", 3.5);. To destruct a tuple we can use pattern matching

let tup = (500, 6.4, 1);
let (x, y, z) = tup;

println!("The value of y is: {y}");

We can also access a tuple element directly by using a period (.) followed by the index of the value we want to access.

• Data Types
• The Slice Type

Vectors

• Two ways to define a Vector:

1. One way is to use the Vec::new() function to create a new vector and fill it with the push() method.
2. The second way, which is simpler is to use the vec![] macro and define your elements inside the square brackets