Rust Notes: Integers and Floats

Published: 2022-02-05

Integers

Integers represent whole numbers. Rust has both unsigned integers and signed integers. unsigned integers cannot be negative, and have a higher positive range than signed integers, that can be negative, but have a lower postive range.

The following table lists the integer literal types in Rust.

LengthUnsignedSigned
8-bitsu8i8
16-bitsu16i16
32-bitsu32i32
64-bitsu64i64
128-bitsu128i128
CPU Architectureusizeisize

The following table lists the formats that are supported for an integer literal definition.

LiteralExample
Decimal42
Hex0x2a
Octal0o52
Binary0b101010
Byte (u8 only)b'Z'

Integer code examples

rust
// i32 by default
let the_answser = 42;

// Annotate the type of integer
let dinner_for_two: i8 = 69;

// Integer suffixing is also supported for type annotation
let its_friday = 420u16; // => 420

// Underscores can help to improve readbility
let you_da_winnah = 1_16_32_5_12_19_40_i64; // => 116325121940

Integer Considerations

  • i32 is the default type if an integer does not include a type annotation.
  • The term u8 and byte are used interchangeably in the Rust community.
  • Underscores (_) can be used to improve the readability of an integer literal, they are ignored by the compiler. EG: 1_000_000

Floats

Floating points represent a number with a fractional component expressed in IEEE-754 format. Rust has two floating point types: f32 and f64.

The following table list the floating point literal types and their bits of precision.

PrecisionType
32-bitsf32
64-bitsf64

Float code examples

rust
// f64 by default
let highly_sexual = 420.69;

// Annotate the type of float
let dinner_for_two: f32 = 69.69;

// Float suffixing is also supported for type annotation
let its_friday = 420.69f32; // => 420.69

// Underscores can help to improve readbility
let you_da_winnah = 420_69.1337_f64; // => 42069.1337

Float Considerations

  • f64 is the default type if a float does not include a type annotation.
  • A float requires a digit before the decimal place (.) in a float definition.
  • Underscores (_) can be used to improve the readability of a float literal, they are ignored by the compiler. EG: 420_69.1337
  • f64 can be slow on a 32-bit architecture.

Tags

#rust