3.1. Variables and Mutability

const vs let

• const declares a constant that must be const expression and the type of it must be annotated.
• let declares a variable, which can be immutable/mutable.

shadowing

• We can shadow variables that have a different type, but we cannot shadow constants.

3.2. Data Types

default numerics

• default integer type is i32, default floating point type is f64 .

char

• Unlike most languages, Rust’s char type has 4 bytes and can represent a Unicode Scalar Value.

tuple

• (a,b,c) can be accessed by index, e.g. tu.0 , tu.1 , etc..
• A tuple without any values () is called unit type, and the value is called unit value. Expressions implicitly return the unit value if they don’t return any other value.

array

• We need to declare array type like

let a: [T; N] = [x1, x2, ..., xn];

T is the element type, N is the number of elements.

3.5. Control Flow

if expressions