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>());
Run§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>>());
RunImplementations§
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.
const: 1.47.0 · sourcepub const fn new(n: usize) -> Option<Self>
pub const fn new(n: usize) -> Option<Self>
Creates a non-zero if the given value is not zero.
sourcepub unsafe fn from_mut_unchecked(n: &mut usize) -> &mut Self
🔬This is a nightly-only experimental API. (nonzero_from_mut
#106290)
pub unsafe fn from_mut_unchecked(n: &mut usize) -> &mut Self
nonzero_from_mut
#106290)Converts a primitive mutable reference to a non-zero mutable reference
without checking whether the referenced value is non-zero.
This results in undefined behavior if *n
is zero.
§Safety
The referenced value must not be currently zero.
sourcepub fn from_mut(n: &mut usize) -> Option<&mut Self>
🔬This is a nightly-only experimental API. (nonzero_from_mut
#106290)
pub fn from_mut(n: &mut usize) -> Option<&mut Self>
nonzero_from_mut
#106290)Converts a primitive mutable reference to a non-zero mutable reference if the referenced integer is not zero.
1.67.0 · sourcepub const BITS: u32 = 64u32
pub const BITS: u32 = 64u32
The size of this non-zero integer type in bits.
This value is equal to usize::BITS
.
§Examples
assert_eq!(NonZeroUsize::BITS, usize::BITS);
Run1.53.0 (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);
Run1.53.0 (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);
Runconst: unstable · sourcepub fn count_ones(self) -> NonZeroU32
🔬This is a nightly-only experimental API. (non_zero_count_ones
#120287)
pub fn count_ones(self) -> NonZeroU32
non_zero_count_ones
#120287)Returns the number of ones in the binary representation of self
.
§Examples
Basic usage:
#![feature(non_zero_count_ones)]
let one = num::NonZeroU32::new(1)?;
let three = num::NonZeroU32::new(3)?;
let a = NonZeroUsize::new(0b100_0000)?;
let b = NonZeroUsize::new(0b100_0011)?;
assert_eq!(a.count_ones(), one);
assert_eq!(b.count_ones(), three);
Run1.70.0 · sourcepub const MAX: Self = _
pub const MAX: Self = _
The largest value that can be represented by this non-zero
integer type,
equal to usize::MAX
.
§Examples
assert_eq!(NonZeroUsize::MAX.get(), usize::MAX);
Run1.64.0 (const: 1.64.0) · sourcepub const fn checked_add(self, other: usize) -> Option<Self>
pub const fn checked_add(self, other: usize) -> Option<Self>
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));
Run1.64.0 (const: 1.64.0) · sourcepub const fn saturating_add(self, other: usize) -> Self
pub const fn saturating_add(self, other: usize) -> Self
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));
Runsourcepub const unsafe fn unchecked_add(self, other: usize) -> Self
🔬This is a nightly-only experimental API. (nonzero_ops
#84186)
pub const unsafe fn unchecked_add(self, other: usize) -> Self
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) });
Run1.64.0 (const: 1.64.0) · sourcepub const fn checked_next_power_of_two(self) -> Option<Self>
pub const fn checked_next_power_of_two(self) -> Option<Self>
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() );
Run1.67.0 (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);
Run1.67.0 (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);
Runconst: 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);
Run1.59.0 (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());
Run1.64.0 (const: 1.64.0) · sourcepub const fn checked_mul(self, other: Self) -> Option<Self>
pub const fn checked_mul(self, other: Self) -> Option<Self>
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));
Run1.64.0 (const: 1.64.0) · sourcepub const fn saturating_mul(self, other: Self) -> Self
pub const fn saturating_mul(self, other: Self) -> Self
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));
Runsourcepub const unsafe fn unchecked_mul(self, other: Self) -> Self
🔬This is a nightly-only experimental API. (nonzero_ops
#84186)
pub const unsafe fn unchecked_mul(self, other: Self) -> Self
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) });
Run1.64.0 (const: 1.64.0) · sourcepub const fn checked_pow(self, other: u32) -> Option<Self>
pub const fn checked_pow(self, other: u32) -> Option<Self>
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));
Run1.64.0 (const: 1.64.0) · sourcepub const fn saturating_pow(self, other: u32) -> Self
pub const fn saturating_pow(self, other: u32) -> Self
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));
RunTrait 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§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 PartialEq for NonZeroUsize
impl PartialEq for NonZeroUsize
source§impl PartialOrd for NonZeroUsize
impl PartialOrd for NonZeroUsize
1.51.0 · 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
.