primitive-types.md

Primitive Types

Scalar Types

Type	Description	Example Values
Integers	Signed (i8, i16, i32, i64, i128, isize) and unsigned (u8, u16, u32, u64, u128, usize).	42, -5i8, 0xFFu8
Floating	f32 and f64 for floating-point numbers.	3.14, -0.001f32
Boolean	bool for true/false values.	true, false
Character	char for a single Unicode scalar value (4 bytes).	'a', '😊', 'Z'

Text Types

Type	Description	Example Values
String Literal	&'static str: Immutable, UTF-8 encoded string slice (e.g., "hello").	"hello", "Rust"
String Slice	&str: Borrowed string data (e.g., substring or string literal).	&"hello"[1..3]
String	String: Growable, heap-allocated UTF-8 string.	String::from("hello")

Compound Types

Type	Description	Example Values
Tuples	Fixed-size, heterogeneous collections.	(42, "hello")
Arrays	Fixed-size, homogeneous collections.	[1, 2, 3], ["a", "b"]

Other Primitives

Type	Description	Example Values
Unit	(): Represents an empty value or return type.	()
Pointers	Raw pointers (*const T, *mut T) and references (&T, &mut T).	&x, &mut y

Key Notes:

• String Literals: The type of "hello" is &'static str (a string slice with a static lifetime).
• String vs. &str: String is owned and heap-allocated; &str is a borrowed view into string data.
• Arrays vs. Slices: Arrays ([T; N]) have a fixed size; slices (&[T]) are dynamically sized views.
• Default Types: i32 for integers, f64 for floats.

Example Usage:

let integer: i32 = 42;
let float: f64 = 3.14;
let string_literal: &str = "hello"; // String literal
let owned_string: String = String::from("Rust");
let tuple: (i32, &str) = (42, "hello");
let array: [i32; 3] = [1, 2, 3];