Numeric types - The Rust Reference

# Numeric types

## Integer types

The unsigned integer types consist of:

Type | Minimum | Maximum
--- | --- | ---
`u8` | 0 | 28-1
`u16` | 0 | 216-1
`u32` | 0 | 232-1
`u64` | 0 | 264-1
`u128` | 0 | 2128-1

The signed two's complement integer types consist of:

Type | Minimum | Maximum
--- | --- | ---
`i8` | -(27) | 27-1
`i16` | -(215) | 215-1
`i32` | -(231) | 231-1
`i64` | -(263) | 263-1
`i128` | -(2127) | 2127-1

## Floating-point types

The IEEE 754-2008 "binary32" and "binary64" floating-point types are `f32` and `f64`, respectively.

## Machine-dependent integer types

The `usize` type is an unsigned integer type with the same number of bits as the platform's pointer type. It can represent every memory address in the process.

The `isize` type is a signed integer type with the same number of bits as the platform's pointer type. The theoretical upper bound on object and array size is the maximum `isize` value. This ensures that `isize` can be used to calculate differences between pointers into an object or array and can address every byte within an object along with one byte past the end.

`usize` and `isize` are at least 16-bits wide.

> Note: Many pieces of Rust code may assume that pointers, `usize`, and `isize` are either 32-bit or 64-bit. As a consequence, 16-bit pointer support is limited and may require explicit care and acknowledgment from a library to support.