Struct core::num::NonZeroUsize  
1.28.0 · source · pub struct NonZeroUsize(/* private fields */);Expand description
An integer that is known not to equal zero.
This enables some memory layout optimization.
For example, Option<NonZeroUsize> is the same size as usize:
use std::mem::size_of;
assert_eq!(size_of::<Option<core::num::NonZeroUsize>>(), size_of::<usize>());Layout
NonZeroUsize is guaranteed to have the same layout and bit validity as usize
with the exception that 0 is not a valid instance.
Option<NonZeroUsize> is guaranteed to be compatible with usize,
including in FFI.
Thanks to the null pointer optimization,
NonZeroUsize and Option<NonZeroUsize>
are guaranteed to have the same size and alignment:
use std::num::NonZeroUsize;
assert_eq!(size_of::<NonZeroUsize>(), size_of::<Option<NonZeroUsize>>());
assert_eq!(align_of::<NonZeroUsize>(), align_of::<Option<NonZeroUsize>>());Implementations§
source§impl NonZeroUsize
 
impl NonZeroUsize
const: 1.28.0 · sourcepub const unsafe fn new_unchecked(n: usize) -> Self
 
pub const unsafe fn new_unchecked(n: usize) -> Self
Creates a non-zero without checking whether the value is non-zero. This results in undefined behaviour if the value is zero.
Safety
The value must not be zero.
source§impl NonZeroUsize
 
impl NonZeroUsize
1.53.0 (const: 1.53.0) · sourcepub const fn leading_zeros(self) -> u32
 
pub const fn leading_zeros(self) -> u32
Returns the number of leading zeros in the binary representation of self.
On many architectures, this function can perform better than leading_zeros() on the underlying integer type, as special handling of zero can be avoided.
Examples
Basic usage:
let n = std::num::NonZeroUsize::new(usize::MAX).unwrap();
assert_eq!(n.leading_zeros(), 0);1.53.0 (const: 1.53.0) · sourcepub const fn trailing_zeros(self) -> u32
 
pub const fn trailing_zeros(self) -> u32
Returns the number of trailing zeros in the binary representation
of self.
On many architectures, this function can perform better than trailing_zeros() on the underlying integer type, as special handling of zero can be avoided.
Examples
Basic usage:
let n = std::num::NonZeroUsize::new(0b0101000).unwrap();
assert_eq!(n.trailing_zeros(), 3);source§impl NonZeroUsize
 
impl NonZeroUsize
1.64.0 (const: 1.64.0) · sourcepub const fn checked_add(self, other: usize) -> Option<NonZeroUsize>
 
pub const fn checked_add(self, other: usize) -> Option<NonZeroUsize>
Adds an unsigned integer to a non-zero value.
Checks for overflow and returns None on overflow.
As a consequence, the result cannot wrap to zero.
Examples
let one = NonZeroUsize::new(1)?;
let two = NonZeroUsize::new(2)?;
let max = NonZeroUsize::new(usize::MAX)?;
assert_eq!(Some(two), one.checked_add(1));
assert_eq!(None, max.checked_add(1));1.64.0 (const: 1.64.0) · sourcepub const fn saturating_add(self, other: usize) -> NonZeroUsize
 
pub const fn saturating_add(self, other: usize) -> NonZeroUsize
Adds an unsigned integer to a non-zero value.
Return NonZeroUsize::MAX on overflow.
Examples
let one = NonZeroUsize::new(1)?;
let two = NonZeroUsize::new(2)?;
let max = NonZeroUsize::new(usize::MAX)?;
assert_eq!(two, one.saturating_add(1));
assert_eq!(max, max.saturating_add(1));sourcepub const unsafe fn unchecked_add(self, other: usize) -> NonZeroUsize
 🔬This is a nightly-only experimental API. (nonzero_ops #84186)
pub const unsafe fn unchecked_add(self, other: usize) -> NonZeroUsize
nonzero_ops #84186)Adds an unsigned integer to a non-zero value,
assuming overflow cannot occur.
Overflow is unchecked, and it is undefined behaviour to overflow
even if the result would wrap to a non-zero value.
The behaviour is undefined as soon as
self + rhs > usize::MAX.
Examples
#![feature(nonzero_ops)]
let one = NonZeroUsize::new(1)?;
let two = NonZeroUsize::new(2)?;
assert_eq!(two, unsafe { one.unchecked_add(1) });1.64.0 (const: 1.64.0) · sourcepub const fn checked_next_power_of_two(self) -> Option<NonZeroUsize>
 
pub const fn checked_next_power_of_two(self) -> Option<NonZeroUsize>
Returns the smallest power of two greater than or equal to n.
Checks for overflow and returns None
if the next power of two is greater than the type’s maximum value.
As a consequence, the result cannot wrap to zero.
Examples
let two = NonZeroUsize::new(2)?;
let three = NonZeroUsize::new(3)?;
let four = NonZeroUsize::new(4)?;
let max = NonZeroUsize::new(usize::MAX)?;
assert_eq!(Some(two), two.checked_next_power_of_two() );
assert_eq!(Some(four), three.checked_next_power_of_two() );
assert_eq!(None, max.checked_next_power_of_two() );1.67.0 (const: 1.67.0) · sourcepub const fn ilog2(self) -> u32
 
pub const fn ilog2(self) -> u32
Returns the base 2 logarithm of the number, rounded down.
This is the same operation as
usize::ilog2,
except that it has no failure cases to worry about
since this value can never be zero.
Examples
assert_eq!(NonZeroUsize::new(7).unwrap().ilog2(), 2);
assert_eq!(NonZeroUsize::new(8).unwrap().ilog2(), 3);
assert_eq!(NonZeroUsize::new(9).unwrap().ilog2(), 3);1.67.0 (const: 1.67.0) · sourcepub const fn ilog10(self) -> u32
 
pub const fn ilog10(self) -> u32
Returns the base 10 logarithm of the number, rounded down.
This is the same operation as
usize::ilog10,
except that it has no failure cases to worry about
since this value can never be zero.
Examples
assert_eq!(NonZeroUsize::new(99).unwrap().ilog10(), 1);
assert_eq!(NonZeroUsize::new(100).unwrap().ilog10(), 2);
assert_eq!(NonZeroUsize::new(101).unwrap().ilog10(), 2);const: unstable · sourcepub fn midpoint(self, rhs: Self) -> Self
 🔬This is a nightly-only experimental API. (num_midpoint #110840)
pub fn midpoint(self, rhs: Self) -> Self
num_midpoint #110840)Calculates the middle point of self and rhs.
midpoint(a, b) is (a + b) >> 1 as if it were performed in a
sufficiently-large signed integral type. This implies that the result is
always rounded towards negative infinity and that no overflow will ever occur.
Examples
#![feature(num_midpoint)]
let one = NonZeroUsize::new(1)?;
let two = NonZeroUsize::new(2)?;
let four = NonZeroUsize::new(4)?;
assert_eq!(one.midpoint(four), two);
assert_eq!(four.midpoint(one), two);source§impl NonZeroUsize
 
impl NonZeroUsize
1.64.0 (const: 1.64.0) · sourcepub const fn checked_mul(self, other: NonZeroUsize) -> Option<NonZeroUsize>
 
pub const fn checked_mul(self, other: NonZeroUsize) -> Option<NonZeroUsize>
Multiplies two non-zero integers together.
Checks for overflow and returns None on overflow.
As a consequence, the result cannot wrap to zero.
Examples
let two = NonZeroUsize::new(2)?;
let four = NonZeroUsize::new(4)?;
let max = NonZeroUsize::new(usize::MAX)?;
assert_eq!(Some(four), two.checked_mul(two));
assert_eq!(None, max.checked_mul(two));1.64.0 (const: 1.64.0) · sourcepub const fn saturating_mul(self, other: NonZeroUsize) -> NonZeroUsize
 
pub const fn saturating_mul(self, other: NonZeroUsize) -> NonZeroUsize
Multiplies two non-zero integers together.
Return NonZeroUsize::MAX on overflow.
Examples
let two = NonZeroUsize::new(2)?;
let four = NonZeroUsize::new(4)?;
let max = NonZeroUsize::new(usize::MAX)?;
assert_eq!(four, two.saturating_mul(two));
assert_eq!(max, four.saturating_mul(max));sourcepub const unsafe fn unchecked_mul(self, other: NonZeroUsize) -> NonZeroUsize
 🔬This is a nightly-only experimental API. (nonzero_ops #84186)
pub const unsafe fn unchecked_mul(self, other: NonZeroUsize) -> NonZeroUsize
nonzero_ops #84186)Multiplies two non-zero integers together,
assuming overflow cannot occur.
Overflow is unchecked, and it is undefined behaviour to overflow
even if the result would wrap to a non-zero value.
The behaviour is undefined as soon as
self * rhs > usize::MAX.
Examples
#![feature(nonzero_ops)]
let two = NonZeroUsize::new(2)?;
let four = NonZeroUsize::new(4)?;
assert_eq!(four, unsafe { two.unchecked_mul(two) });1.64.0 (const: 1.64.0) · sourcepub const fn checked_pow(self, other: u32) -> Option<NonZeroUsize>
 
pub const fn checked_pow(self, other: u32) -> Option<NonZeroUsize>
Raises non-zero value to an integer power.
Checks for overflow and returns None on overflow.
As a consequence, the result cannot wrap to zero.
Examples
let three = NonZeroUsize::new(3)?;
let twenty_seven = NonZeroUsize::new(27)?;
let half_max = NonZeroUsize::new(usize::MAX / 2)?;
assert_eq!(Some(twenty_seven), three.checked_pow(3));
assert_eq!(None, half_max.checked_pow(3));1.64.0 (const: 1.64.0) · sourcepub const fn saturating_pow(self, other: u32) -> NonZeroUsize
 
pub const fn saturating_pow(self, other: u32) -> NonZeroUsize
Raise non-zero value to an integer power.
Return NonZeroUsize::MAX on overflow.
Examples
let three = NonZeroUsize::new(3)?;
let twenty_seven = NonZeroUsize::new(27)?;
let max = NonZeroUsize::new(usize::MAX)?;
assert_eq!(twenty_seven, three.saturating_pow(3));
assert_eq!(max, max.saturating_pow(3));source§impl NonZeroUsize
 
impl NonZeroUsize
1.59.0 (const: 1.59.0) · sourcepub const fn is_power_of_two(self) -> bool
 
pub const fn is_power_of_two(self) -> bool
Returns true if and only if self == (1 << k) for some k.
On many architectures, this function can perform better than is_power_of_two()
on the underlying integer type, as special handling of zero can be avoided.
Examples
Basic usage:
let eight = std::num::NonZeroUsize::new(8).unwrap();
assert!(eight.is_power_of_two());
let ten = std::num::NonZeroUsize::new(10).unwrap();
assert!(!ten.is_power_of_two());source§impl NonZeroUsize
 
impl NonZeroUsize
source§impl NonZeroUsize
 
impl NonZeroUsize
Trait Implementations§
source§impl Binary for NonZeroUsize
 
impl Binary for NonZeroUsize
1.45.0 · source§impl BitOr<NonZeroUsize> for usize
 
impl BitOr<NonZeroUsize> for usize
§type Output = NonZeroUsize
 
type Output = NonZeroUsize
| operator.1.45.0 · source§impl BitOr<usize> for NonZeroUsize
 
impl BitOr<usize> for NonZeroUsize
1.45.0 · source§impl BitOr for NonZeroUsize
 
impl BitOr for NonZeroUsize
1.45.0 · source§impl BitOrAssign<usize> for NonZeroUsize
 
impl BitOrAssign<usize> for NonZeroUsize
source§fn bitor_assign(&mut self, rhs: usize)
 
fn bitor_assign(&mut self, rhs: usize)
|= operation. Read more1.45.0 · source§impl BitOrAssign for NonZeroUsize
 
impl BitOrAssign for NonZeroUsize
source§fn bitor_assign(&mut self, rhs: Self)
 
fn bitor_assign(&mut self, rhs: Self)
|= operation. Read moresource§impl Clone for NonZeroUsize
 
impl Clone for NonZeroUsize
source§fn clone(&self) -> NonZeroUsize
 
fn clone(&self) -> NonZeroUsize
1.0.0 · source§fn clone_from(&mut self, source: &Self)
 
fn clone_from(&mut self, source: &Self)
source. Read moresource§impl Debug for NonZeroUsize
 
impl Debug for NonZeroUsize
source§impl Display for NonZeroUsize
 
impl Display for NonZeroUsize
1.51.0 · source§impl Div<NonZeroUsize> for usize
 
impl Div<NonZeroUsize> for usize
source§impl From<Alignment> for NonZeroUsize
 
impl From<Alignment> for NonZeroUsize
source§fn from(align: Alignment) -> NonZeroUsize
 
fn from(align: Alignment) -> NonZeroUsize
1.41.0 · source§impl From<NonZeroU16> for NonZeroUsize
 
impl From<NonZeroU16> for NonZeroUsize
source§fn from(small: NonZeroU16) -> Self
 
fn from(small: NonZeroU16) -> Self
Converts NonZeroU16 to NonZeroUsize losslessly.
1.41.0 · source§impl From<NonZeroU8> for NonZeroUsize
 
impl From<NonZeroU8> for NonZeroUsize
1.31.0 · source§impl From<NonZeroUsize> for usize
 
impl From<NonZeroUsize> for usize
source§fn from(nonzero: NonZeroUsize) -> Self
 
fn from(nonzero: NonZeroUsize) -> Self
Converts a NonZeroUsize into an usize
1.35.0 · source§impl FromStr for NonZeroUsize
 
impl FromStr for NonZeroUsize
source§impl Hash for NonZeroUsize
 
impl Hash for NonZeroUsize
source§impl LowerHex for NonZeroUsize
 
impl LowerHex for NonZeroUsize
source§impl Octal for NonZeroUsize
 
impl Octal for NonZeroUsize
source§impl Ord for NonZeroUsize
 
impl Ord for NonZeroUsize
source§fn cmp(&self, other: &NonZeroUsize) -> Ordering
 
fn cmp(&self, other: &NonZeroUsize) -> Ordering
1.21.0 · source§fn max(self, other: Self) -> Selfwhere
    Self: Sized,
 
fn max(self, other: Self) -> Selfwhere Self: Sized,
source§impl PartialEq for NonZeroUsize
 
impl PartialEq for NonZeroUsize
source§fn eq(&self, other: &NonZeroUsize) -> bool
 
fn eq(&self, other: &NonZeroUsize) -> bool
self and other values to be equal, and is used
by ==.source§impl PartialOrd for NonZeroUsize
 
impl PartialOrd for NonZeroUsize
source§fn partial_cmp(&self, other: &NonZeroUsize) -> Option<Ordering>
 
fn partial_cmp(&self, other: &NonZeroUsize) -> Option<Ordering>
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
 
fn le(&self, other: &Rhs) -> bool
self and other) and is used by the <=
operator. Read more1.51.0 · source§impl Rem<NonZeroUsize> for usize
 
impl Rem<NonZeroUsize> for usize
1.49.0 · source§impl TryFrom<NonZeroI128> for NonZeroUsize
 
impl TryFrom<NonZeroI128> for NonZeroUsize
source§fn try_from(value: NonZeroI128) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroI128) -> Result<Self, Self::Error>
Attempts to convert NonZeroI128 to NonZeroUsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroI16> for NonZeroUsize
 
impl TryFrom<NonZeroI16> for NonZeroUsize
source§fn try_from(value: NonZeroI16) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroI16) -> Result<Self, Self::Error>
Attempts to convert NonZeroI16 to NonZeroUsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroI32> for NonZeroUsize
 
impl TryFrom<NonZeroI32> for NonZeroUsize
source§fn try_from(value: NonZeroI32) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroI32) -> Result<Self, Self::Error>
Attempts to convert NonZeroI32 to NonZeroUsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroI64> for NonZeroUsize
 
impl TryFrom<NonZeroI64> for NonZeroUsize
source§fn try_from(value: NonZeroI64) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroI64) -> Result<Self, Self::Error>
Attempts to convert NonZeroI64 to NonZeroUsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroI8> for NonZeroUsize
 
impl TryFrom<NonZeroI8> for NonZeroUsize
1.49.0 · source§impl TryFrom<NonZeroIsize> for NonZeroUsize
 
impl TryFrom<NonZeroIsize> for NonZeroUsize
source§fn try_from(value: NonZeroIsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroIsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroIsize to NonZeroUsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroU128> for NonZeroUsize
 
impl TryFrom<NonZeroU128> for NonZeroUsize
source§fn try_from(value: NonZeroU128) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroU128) -> Result<Self, Self::Error>
Attempts to convert NonZeroU128 to NonZeroUsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroU32> for NonZeroUsize
 
impl TryFrom<NonZeroU32> for NonZeroUsize
source§fn try_from(value: NonZeroU32) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroU32) -> Result<Self, Self::Error>
Attempts to convert NonZeroU32 to NonZeroUsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroU64> for NonZeroUsize
 
impl TryFrom<NonZeroU64> for NonZeroUsize
source§fn try_from(value: NonZeroU64) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroU64) -> Result<Self, Self::Error>
Attempts to convert NonZeroU64 to NonZeroUsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
source§impl TryFrom<NonZeroUsize> for Alignment
 
impl TryFrom<NonZeroUsize> for Alignment
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroI128
 
impl TryFrom<NonZeroUsize> for NonZeroI128
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroI128.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroI16
 
impl TryFrom<NonZeroUsize> for NonZeroI16
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroI16.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroI32
 
impl TryFrom<NonZeroUsize> for NonZeroI32
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroI32.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroI64
 
impl TryFrom<NonZeroUsize> for NonZeroI64
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroI64.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroI8
 
impl TryFrom<NonZeroUsize> for NonZeroI8
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroI8.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroIsize
 
impl TryFrom<NonZeroUsize> for NonZeroIsize
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroIsize.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroU128
 
impl TryFrom<NonZeroUsize> for NonZeroU128
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroU128.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroU16
 
impl TryFrom<NonZeroUsize> for NonZeroU16
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroU16.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroU32
 
impl TryFrom<NonZeroUsize> for NonZeroU32
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroU32.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroU64
 
impl TryFrom<NonZeroUsize> for NonZeroU64
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroU64.
§type Error = TryFromIntError
 
type Error = TryFromIntError
1.49.0 · source§impl TryFrom<NonZeroUsize> for NonZeroU8
 
impl TryFrom<NonZeroUsize> for NonZeroU8
source§fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
 
fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>
Attempts to convert NonZeroUsize to NonZeroU8.