6.1 Integers

The Integer Types are available in signed and unsigned flavours, from 8 bits to 128 bits. The unsigned versions are: u8, u16, u32, u64 and u128. The signed versions are: i8, i16, i32, i64 and i128.

Table 1 provides a list of available operators.

6.1.1Default type¶

If unspecified, an integer is of type i32:

let i = 15; // Default type: i32
i

6.1.2Specifying the type¶

To set explicitly the integer type, we can either set it to the variable or the value:

let i: u8 = 27;         //  8-bit unsigned integer
let j     = 516i16;     // 16-bit   signed integer
(i, j)

6.1.3Separator¶

For big literal numbers, the underscore can be used to ease reading:

let n = 1_000_000_000;
let m = 12_34_56;
(n, m)

6.1.4Binary, octal and hexadecimal¶

Binary, octal and hexadecimal numbers can be defined using the appropriate prefix (0b, 0o, 0x):

let bin = 0b0100_0001_1110;
let oct = 0o466;
let hex = 0x23ff_89c8;
(bin, oct, hex)

6.1.5Size types¶

Two architecture dependent integer types exist to store sizes (e.g.: array sizes, string sizes). One is signed and the other unsigned:

let n: isize = -1;
let m: usize = 8000;
(n, m)

6.1.6Character byte¶

A special notation exists to define a character byte, which is stored as a plain 8-bit integer (u8):

let n = b'A';
n

The type of n will be u8.

6.1.7Operations¶

Examples of computing a remainder:

(11 % 3, -11 % 3, 11 % -3, -11 % -3)

A division:

(11 / 3, -11 / 3, 11 / -3, -11 / -3)

6.1.8Type related constants¶

Some constants are directly accessible on the primitive types: i8, i16, i32, i64, u8, u16, u32, u64.

Example for 8-bit unsigned integer:

println!("BITS: {}", u8::BITS);
println!("MIN: {}",  u8::MIN);
println!("MAX: {}",  u8::MAX);

BITS: 8

MIN: 0

MAX: 255

Example for 32-bit unsigned integer:

println!("BITS: {}", u32::BITS);
println!("MIN: {}",  u32::MIN);
println!("MAX: {}",  u32::MAX);

BITS: 32

MIN: 0

MAX: 4294967295

Example for 64-bit signed integer:

println!("BITS: {}", i64::BITS);
println!("MIN: {}",  i64::MIN);
println!("MAX: {}",  i64::MAX);

BITS: 64

MIN: -9223372036854775808

MAX: 9223372036854775807