Primitive Type i8 <img src="../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path">

impl i8

1.43.0 · source

pub const MIN: i8 = -128i8

The smallest value that can be represented by this integer type (−2⁷).

pub const MAX: i8 = 127i8

The largest value that can be represented by this integer type (2⁷ − 1).

pub const BITS: u32 = 8u32

The size of this integer type in bits.

pub fn from_str_radix(src: &str, radix: u32) -> Result<i8, ParseIntError>

Converts a string slice in a given base to an integer.

The string is expected to be an optional + or - sign followed by digits. Leading and trailing whitespace represent an error. Digits are a subset of these characters, depending on radix:

0-9
a-z
A-Z

Panics

This function panics if radix is not in the range from 2 to 36.

pub const fn count_ones(self) -> u32

Returns the number of ones in the binary representation of self.

pub const fn count_zeros(self) -> u32

Returns the number of zeros in the binary representation of self.

pub const fn leading_zeros(self) -> u32

Returns the number of leading zeros in the binary representation of self.

Depending on what you’re doing with the value, you might also be interested in the ilog2 function which returns a consistent number, even if the type widens.

pub const fn trailing_zeros(self) -> u32

Returns the number of trailing zeros in the binary representation of self.

pub const fn leading_ones(self) -> u32

Returns the number of leading ones in the binary representation of self.

pub const fn trailing_ones(self) -> u32

Returns the number of trailing ones in the binary representation of self.

pub const fn rotate_left(self, n: u32) -> i8

Shifts the bits to the left by a specified amount, n, wrapping the truncated bits to the end of the resulting integer.

Please note this isn’t the same operation as the << shifting operator!

pub const fn rotate_right(self, n: u32) -> i8

Shifts the bits to the right by a specified amount, n, wrapping the truncated bits to the beginning of the resulting integer.

Please note this isn’t the same operation as the >> shifting operator!

pub const fn swap_bytes(self) -> i8

Reverses the byte order of the integer.

pub const fn reverse_bits(self) -> i8

Reverses the order of bits in the integer. The least significant bit becomes the most significant bit, second least-significant bit becomes second most-significant bit, etc.

pub const fn from_be(x: i8) -> i8

Converts an integer from big endian to the target’s endianness.

On big endian this is a no-op. On little endian the bytes are swapped.

pub const fn from_le(x: i8) -> i8

Converts an integer from little endian to the target’s endianness.

On little endian this is a no-op. On big endian the bytes are swapped.

pub const fn to_be(self) -> i8

Converts self to big endian from the target’s endianness.

On big endian this is a no-op. On little endian the bytes are swapped.

pub const fn to_le(self) -> i8

pub const fn checked_div(self, rhs: i8) -> Option<i8>

Checked integer division. Computes self / rhs, returning None if rhs == 0 or the division results in overflow.

pub const fn checked_div_euclid(self, rhs: i8) -> Option<i8>

Checked Euclidean division. Computes self.div_euclid(rhs), returning None if rhs == 0 or the division results in overflow.

pub const fn checked_rem(self, rhs: i8) -> Option<i8>

Checked integer remainder. Computes self % rhs, returning None if rhs == 0 or the division results in overflow.

pub const fn checked_rem_euclid(self, rhs: i8) -> Option<i8>

Checked Euclidean remainder. Computes self.rem_euclid(rhs), returning None if rhs == 0 or the division results in overflow.

pub const fn checked_neg(self) -> Option<i8>

Checked negation. Computes -self, returning None if self == MIN.

pub const fn checked_shl(self, rhs: u32) -> Option<i8>

Checked shift left. Computes self << rhs, returning None if rhs is larger than or equal to the number of bits in self.

pub unsafe fn unchecked_shl(self, rhs: u32) -> i8

🔬This is a nightly-only experimental API. (unchecked_math #85122)

Unchecked shift left. Computes self << rhs, assuming that rhs is less than the number of bits in self.

Safety

This results in undefined behavior if rhs is larger than or equal to the number of bits in self, i.e. when checked_shl would return None.

1.7.0 (const: 1.47.0) · source

pub const fn checked_shr(self, rhs: u32) -> Option<i8>

Checked shift right. Computes self >> rhs, returning None if rhs is larger than or equal to the number of bits in self.

pub unsafe fn unchecked_shr(self, rhs: u32) -> i8

🔬This is a nightly-only experimental API. (unchecked_math #85122)

Unchecked shift right. Computes self >> rhs, assuming that rhs is less than the number of bits in self.

Safety

This results in undefined behavior if rhs is larger than or equal to the number of bits in self, i.e. when checked_shr would return None.

1.13.0 (const: 1.47.0) · source

pub const fn checked_abs(self) -> Option<i8>

Checked absolute value. Computes self.abs(), returning None if self == MIN.

pub const fn checked_pow(self, exp: u32) -> Option<i8>

Checked exponentiation. Computes self.pow(exp), returning None if overflow occurred.

pub const fn saturating_add(self, rhs: i8) -> i8

Saturating integer addition. Computes self + rhs, saturating at the numeric bounds instead of overflowing.

pub const fn saturating_add_unsigned(self, rhs: u8) -> i8

Saturating addition with an unsigned integer. Computes self + rhs, saturating at the numeric bounds instead of overflowing.

pub const fn saturating_sub(self, rhs: i8) -> i8

Saturating integer subtraction. Computes self - rhs, saturating at the numeric bounds instead of overflowing.

pub const fn saturating_sub_unsigned(self, rhs: u8) -> i8

Saturating subtraction with an unsigned integer. Computes self - rhs, saturating at the numeric bounds instead of overflowing.

pub const fn saturating_neg(self) -> i8

Saturating integer negation. Computes -self, returning MAX if self == MIN instead of overflowing.

pub const fn saturating_abs(self) -> i8

Saturating absolute value. Computes self.abs(), returning MAX if self == MIN instead of overflowing.

pub const fn saturating_mul(self, rhs: i8) -> i8

Saturating integer multiplication. Computes self * rhs, saturating at the numeric bounds instead of overflowing.

pub const fn saturating_div(self, rhs: i8) -> i8

Saturating integer division. Computes self / rhs, saturating at the numeric bounds instead of overflowing.

pub const fn saturating_pow(self, exp: u32) -> i8

Saturating integer exponentiation. Computes self.pow(exp), saturating at the numeric bounds instead of overflowing.

pub const fn wrapping_add(self, rhs: i8) -> i8

Wrapping (modular) addition. Computes self + rhs, wrapping around at the boundary of the type.

pub const fn wrapping_add_unsigned(self, rhs: u8) -> i8

Wrapping (modular) addition with an unsigned integer. Computes self + rhs, wrapping around at the boundary of the type.

pub const fn wrapping_sub(self, rhs: i8) -> i8

Wrapping (modular) subtraction. Computes self - rhs, wrapping around at the boundary of the type.

pub const fn wrapping_sub_unsigned(self, rhs: u8) -> i8

Wrapping (modular) subtraction with an unsigned integer. Computes self - rhs, wrapping around at the boundary of the type.

pub const fn wrapping_mul(self, rhs: i8) -> i8

Wrapping (modular) multiplication. Computes self * rhs, wrapping around at the boundary of the type.

pub const fn wrapping_div(self, rhs: i8) -> i8

Wrapping (modular) division. Computes self / rhs, wrapping around at the boundary of the type.

The only case where such wrapping can occur is when one divides MIN / -1 on a signed type (where MIN is the negative minimal value for the type); this is equivalent to -MIN, a positive value that is too large to represent in the type. In such a case, this function returns MIN itself.

Panics

This function will panic if rhs is 0.

Examples

Basic usage:

assert_eq!(100i8.wrapping_div(10), 10);
assert_eq!((-128i8).wrapping_div(-1), -128);

1.38.0 (const: 1.52.0) · source

pub const fn wrapping_div_euclid(self, rhs: i8) -> i8

Wrapping Euclidean division. Computes self.div_euclid(rhs), wrapping around at the boundary of the type.

Wrapping will only occur in MIN / -1 on a signed type (where MIN is the negative minimal value for the type). This is equivalent to -MIN, a positive value that is too large to represent in the type. In this case, this method returns MIN itself.

Panics

This function will panic if rhs is 0.

Examples

Basic usage:

assert_eq!(100i8.wrapping_div_euclid(10), 10);
assert_eq!((-128i8).wrapping_div_euclid(-1), -128);

1.2.0 (const: 1.52.0) · source

pub const fn wrapping_rem(self, rhs: i8) -> i8

Wrapping (modular) remainder. Computes self % rhs, wrapping around at the boundary of the type.

Such wrap-around never actually occurs mathematically; implementation artifacts make x % y invalid for MIN / -1 on a signed type (where MIN is the negative minimal value). In such a case, this function returns 0.

Panics

This function will panic if rhs is 0.

Examples

Basic usage:

assert_eq!(100i8.wrapping_rem(10), 0);
assert_eq!((-128i8).wrapping_rem(-1), 0);

1.38.0 (const: 1.52.0) · source

pub const fn wrapping_rem_euclid(self, rhs: i8) -> i8

Wrapping Euclidean remainder. Computes self.rem_euclid(rhs), wrapping around at the boundary of the type.

Wrapping will only occur in MIN % -1 on a signed type (where MIN is the negative minimal value for the type). In this case, this method returns 0.

Panics

This function will panic if rhs is 0.

Examples

Basic usage:

assert_eq!(100i8.wrapping_rem_euclid(10), 0);
assert_eq!((-128i8).wrapping_rem_euclid(-1), 0);

1.2.0 (const: 1.32.0) · source

pub const fn wrapping_neg(self) -> i8

Wrapping (modular) negation. Computes -self, wrapping around at the boundary of the type.

The only case where such wrapping can occur is when one negates MIN on a signed type (where MIN is the negative minimal value for the type); this is a positive value that is too large to represent in the type. In such a case, this function returns MIN itself.

Examples

Basic usage:

assert_eq!(100i8.wrapping_neg(), -100);
assert_eq!(i8::MIN.wrapping_neg(), i8::MIN);

1.2.0 (const: 1.32.0) · source

pub const fn wrapping_shl(self, rhs: u32) -> i8

Panic-free bitwise shift-left; yields self << mask(rhs), where mask removes any high-order bits of rhs that would cause the shift to exceed the bitwidth of the type.

Note that this is not the same as a rotate-left; the RHS of a wrapping shift-left is restricted to the range of the type, rather than the bits shifted out of the LHS being returned to the other end. The primitive integer types all implement a rotate_left function, which may be what you want instead.

Examples

Basic usage:

assert_eq!((-1i8).wrapping_shl(7), -128);
assert_eq!((-1i8).wrapping_shl(128), -1);

1.2.0 (const: 1.32.0) · source

pub const fn wrapping_shr(self, rhs: u32) -> i8

Panic-free bitwise shift-right; yields self >> mask(rhs), where mask removes any high-order bits of rhs that would cause the shift to exceed the bitwidth of the type.

Note that this is not the same as a rotate-right; the RHS of a wrapping shift-right is restricted to the range of the type, rather than the bits shifted out of the LHS being returned to the other end. The primitive integer types all implement a rotate_right function, which may be what you want instead.

Examples

Basic usage:

assert_eq!((-128i8).wrapping_shr(7), -1);
assert_eq!((-128i16).wrapping_shr(64), -128);

1.13.0 (const: 1.32.0) · source

pub const fn wrapping_abs(self) -> i8

Wrapping (modular) absolute value. Computes self.abs(), wrapping around at the boundary of the type.

The only case where such wrapping can occur is when one takes the absolute value of the negative minimal value for the type; this is a positive value that is too large to represent in the type. In such a case, this function returns MIN itself.

Examples

Basic usage:

assert_eq!(100i8.wrapping_abs(), 100);
assert_eq!((-100i8).wrapping_abs(), 100);
assert_eq!(i8::MIN.wrapping_abs(), i8::MIN);
assert_eq!((-128i8).wrapping_abs() as u8, 128);

1.51.0 (const: 1.51.0) · source

pub const fn unsigned_abs(self) -> u8

Computes the absolute value of self without any wrapping or panicking.

Examples

Basic usage:

assert_eq!(100i8.unsigned_abs(), 100u8);
assert_eq!((-100i8).unsigned_abs(), 100u8);
assert_eq!((-128i8).unsigned_abs(), 128u8);

1.34.0 (const: 1.50.0) · source

pub const fn wrapping_pow(self, exp: u32) -> i8

Wrapping (modular) exponentiation. Computes self.pow(exp), wrapping around at the boundary of the type.

Examples

Basic usage:

assert_eq!(3i8.wrapping_pow(4), 81);
assert_eq!(3i8.wrapping_pow(5), -13);
assert_eq!(3i8.wrapping_pow(6), -39);

1.7.0 (const: 1.32.0) · source

pub const fn overflowing_add(self, rhs: i8) -> (i8, bool)

Calculates self + rhs

Returns a tuple of the addition along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

Basic usage:

assert_eq!(5i8.overflowing_add(2), (7, false));
assert_eq!(i8::MAX.overflowing_add(1), (i8::MIN, true));

const: unstable · source

pub fn carrying_add(self, rhs: i8, carry: bool) -> (i8, bool)

🔬This is a nightly-only experimental API. (bigint_helper_methods #85532)

Calculates self + rhs + carry and checks for overflow.

Performs “ternary addition” of two integer operands and a carry-in bit, and returns a tuple of the sum along with a boolean indicating whether an arithmetic overflow would occur. On overflow, the wrapped value is returned.

This allows chaining together multiple additions to create a wider addition, and can be useful for bignum addition. This method should only be used for the most significant word; for the less significant words the unsigned method u8::carrying_add should be used.

The output boolean returned by this method is not a carry flag, and should not be added to a more significant word.

If the input carry is false, this method is equivalent to overflowing_add.

Examples

#![feature(bigint_helper_methods)]
// Only the most significant word is signed.
//
//   10  MAX    (a = 10 × 2^8 + 2^8 - 1)
// + -5    9    (b = -5 × 2^8 + 9)
// ---------
//    6    8    (sum = 6 × 2^8 + 8)

let (a1, a0): (i8, u8) = (10, u8::MAX);
let (b1, b0): (i8, u8) = (-5, 9);
let carry0 = false;

// u8::carrying_add for the less significant words
let (sum0, carry1) = a0.carrying_add(b0, carry0);
assert_eq!(carry1, true);

// i8::carrying_add for the most significant word
let (sum1, overflow) = a1.carrying_add(b1, carry1);
assert_eq!(overflow, false);

assert_eq!((sum1, sum0), (6, 8));

1.66.0 (const: 1.66.0) · source

pub const fn overflowing_add_unsigned(self, rhs: u8) -> (i8, bool)

Calculates self + rhs with an unsigned rhs

Returns a tuple of the addition along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

Basic usage:

assert_eq!(1i8.overflowing_add_unsigned(2), (3, false));
assert_eq!((i8::MIN).overflowing_add_unsigned(u8::MAX), (i8::MAX, false));
assert_eq!((i8::MAX - 2).overflowing_add_unsigned(3), (i8::MIN, true));

1.7.0 (const: 1.32.0) · source

pub const fn overflowing_sub(self, rhs: i8) -> (i8, bool)

Calculates self - rhs

Returns a tuple of the subtraction along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

Basic usage:

assert_eq!(5i8.overflowing_sub(2), (3, false));
assert_eq!(i8::MIN.overflowing_sub(1), (i8::MAX, true));

const: unstable · source

pub fn borrowing_sub(self, rhs: i8, borrow: bool) -> (i8, bool)

🔬This is a nightly-only experimental API. (bigint_helper_methods #85532)

Calculates self − rhs − borrow and checks for overflow.

Performs “ternary subtraction” by subtracting both an integer operand and a borrow-in bit from self, and returns a tuple of the difference along with a boolean indicating whether an arithmetic overflow would occur. On overflow, the wrapped value is returned.

This allows chaining together multiple subtractions to create a wider subtraction, and can be useful for bignum subtraction. This method should only be used for the most significant word; for the less significant words the unsigned method u8::borrowing_sub should be used.

The output boolean returned by this method is not a borrow flag, and should not be subtracted from a more significant word.

If the input borrow is false, this method is equivalent to overflowing_sub.

Examples

#![feature(bigint_helper_methods)]
// Only the most significant word is signed.
//
//    6    8    (a = 6 × 2^8 + 8)
// - -5    9    (b = -5 × 2^8 + 9)
// ---------
//   10  MAX    (diff = 10 × 2^8 + 2^8 - 1)

let (a1, a0): (i8, u8) = (6, 8);
let (b1, b0): (i8, u8) = (-5, 9);
let borrow0 = false;

// u8::borrowing_sub for the less significant words
let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
assert_eq!(borrow1, true);

// i8::borrowing_sub for the most significant word
let (diff1, overflow) = a1.borrowing_sub(b1, borrow1);
assert_eq!(overflow, false);

assert_eq!((diff1, diff0), (10, u8::MAX));

1.66.0 (const: 1.66.0) · source

pub const fn overflowing_sub_unsigned(self, rhs: u8) -> (i8, bool)

Calculates self - rhs with an unsigned rhs

Returns a tuple of the subtraction along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

Basic usage:

assert_eq!(1i8.overflowing_sub_unsigned(2), (-1, false));
assert_eq!((i8::MAX).overflowing_sub_unsigned(u8::MAX), (i8::MIN, false));
assert_eq!((i8::MIN + 2).overflowing_sub_unsigned(3), (i8::MAX, true));

1.7.0 (const: 1.32.0) · source

pub const fn overflowing_mul(self, rhs: i8) -> (i8, bool)

Calculates the multiplication of self and rhs.

Returns a tuple of the multiplication along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

Basic usage:

assert_eq!(5i8.overflowing_mul(2), (10, false));
assert_eq!(1_000_000_000i32.overflowing_mul(10), (1410065408, true));

1.7.0 (const: 1.52.0) · source

pub const fn overflowing_div(self, rhs: i8) -> (i8, bool)

Calculates the divisor when self is divided by rhs.

Returns a tuple of the divisor along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would occur then self is returned.

Panics

This function will panic if rhs is 0.

Examples

Basic usage:

assert_eq!(5i8.overflowing_div(2), (2, false));
assert_eq!(i8::MIN.overflowing_div(-1), (i8::MIN, true));

1.38.0 (const: 1.52.0) · source

pub const fn overflowing_div_euclid(self, rhs: i8) -> (i8, bool)

Calculates the quotient of Euclidean division self.div_euclid(rhs).

Returns a tuple of the divisor along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would occur then self is returned.

Panics

This function will panic if rhs is 0.

Examples

Basic usage:

assert_eq!(5i8.overflowing_div_euclid(2), (2, false));
assert_eq!(i8::MIN.overflowing_div_euclid(-1), (i8::MIN, true));

1.7.0 (const: 1.52.0) · source

pub const fn overflowing_rem(self, rhs: i8) -> (i8, bool)

Calculates the remainder when self is divided by rhs.

Returns a tuple of the remainder after dividing along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would occur then 0 is returned.

Panics

This function will panic if rhs is 0.

Examples

Basic usage:

assert_eq!(5i8.overflowing_rem(2), (1, false));
assert_eq!(i8::MIN.overflowing_rem(-1), (0, true));

1.38.0 (const: 1.52.0) · source

pub const fn overflowing_rem_euclid(self, rhs: i8) -> (i8, bool)

Overflowing Euclidean remainder. Calculates self.rem_euclid(rhs).

Returns a tuple of the remainder after dividing along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would occur then 0 is returned.

Panics

This function will panic if rhs is 0.

Examples

Basic usage:

assert_eq!(5i8.overflowing_rem_euclid(2), (1, false));
assert_eq!(i8::MIN.overflowing_rem_euclid(-1), (0, true));

1.7.0 (const: 1.32.0) · source

pub const fn overflowing_neg(self) -> (i8, bool)

Negates self, overflowing if this is equal to the minimum value.

Returns a tuple of the negated version of self along with a boolean indicating whether an overflow happened. If self is the minimum value (e.g., i32::MIN for values of type i32), then the minimum value will be returned again and true will be returned for an overflow happening.

Examples

Basic usage:

assert_eq!(2i8.overflowing_neg(), (-2, false));
assert_eq!(i8::MIN.overflowing_neg(), (i8::MIN, true));

1.7.0 (const: 1.32.0) · source

pub const fn overflowing_shl(self, rhs: u32) -> (i8, bool)

Shifts self left by rhs bits.

Returns a tuple of the shifted version of self along with a boolean indicating whether the shift value was larger than or equal to the number of bits. If the shift value is too large, then value is masked (N-1) where N is the number of bits, and this value is then used to perform the shift.

Examples

Basic usage:

assert_eq!(0x1i8.overflowing_shl(4), (0x10, false));
assert_eq!(0x1i32.overflowing_shl(36), (0x10, true));

1.7.0 (const: 1.32.0) · source

pub const fn overflowing_shr(self, rhs: u32) -> (i8, bool)

Shifts self right by rhs bits.

Returns a tuple of the shifted version of self along with a boolean indicating whether the shift value was larger than or equal to the number of bits. If the shift value is too large, then value is masked (N-1) where N is the number of bits, and this value is then used to perform the shift.

Examples

Basic usage:

assert_eq!(0x10i8.overflowing_shr(4), (0x1, false));
assert_eq!(0x10i32.overflowing_shr(36), (0x1, true));

1.13.0 (const: 1.32.0) · source

pub const fn overflowing_abs(self) -> (i8, bool)

Computes the absolute value of self.

Returns a tuple of the absolute version of self along with a boolean indicating whether an overflow happened. If self is the minimum value (e.g., i8::MIN for values of type i8), then the minimum value will be returned again and true will be returned for an overflow happening.

Examples

Basic usage:

assert_eq!(10i8.overflowing_abs(), (10, false));
assert_eq!((-10i8).overflowing_abs(), (10, false));
assert_eq!((i8::MIN).overflowing_abs(), (i8::MIN, true));

1.34.0 (const: 1.50.0) · source

pub const fn overflowing_pow(self, exp: u32) -> (i8, bool)

Raises self to the power of exp, using exponentiation by squaring.

Returns a tuple of the exponentiation along with a bool indicating whether an overflow happened.

Examples

Basic usage:

assert_eq!(3i8.overflowing_pow(4), (81, false));
assert_eq!(3i8.overflowing_pow(5), (-13, true));

const: 1.50.0 · source

pub const fn pow(self, exp: u32) -> i8

Raises self to the power of exp, using exponentiation by squaring.

Examples

Basic usage:

let x: i8 = 2; // or any other integer type

assert_eq!(x.pow(5), 32);

1.38.0 (const: 1.52.0) · source

pub const fn div_euclid(self, rhs: i8) -> i8

Calculates the quotient of Euclidean division of self by rhs.

This computes the integer q such that self = q * rhs + r, with r = self.rem_euclid(rhs) and 0 <= r < abs(rhs).

In other words, the result is self / rhs rounded to the integer q such that self >= q * rhs. If self > 0, this is equal to round towards zero (the default in Rust); if self < 0, this is equal to round towards +/- infinity.

Panics

This function will panic if rhs is 0 or the division results in overflow.

Examples

Basic usage:

let a: i8 = 7; // or any other integer type
let b = 4;

assert_eq!(a.div_euclid(b), 1); // 7 >= 4 * 1
assert_eq!(a.div_euclid(-b), -1); // 7 >= -4 * -1
assert_eq!((-a).div_euclid(b), -2); // -7 >= 4 * -2
assert_eq!((-a).div_euclid(-b), 2); // -7 >= -4 * 2

1.38.0 (const: 1.52.0) · source

pub const fn rem_euclid(self, rhs: i8) -> i8

Calculates the least nonnegative remainder of self (mod rhs).

This is done as if by the Euclidean division algorithm – given r = self.rem_euclid(rhs), self = rhs * self.div_euclid(rhs) + r, and 0 <= r < abs(rhs).

Panics

This function will panic if rhs is 0 or the division results in overflow.

Examples

Basic usage:

let a: i8 = 7; // or any other integer type
let b = 4;

assert_eq!(a.rem_euclid(b), 3);
assert_eq!((-a).rem_euclid(b), 1);
assert_eq!(a.rem_euclid(-b), 3);
assert_eq!((-a).rem_euclid(-b), 1);

pub const fn div_floor(self, rhs: i8) -> i8

🔬This is a nightly-only experimental API. (int_roundings #88581)

Calculates the quotient of self and rhs, rounding the result towards negative infinity.

Panics

This function will panic if rhs is zero.

Overflow behavior

On overflow, this function will panic if overflow checks are enabled (default in debug mode) and wrap if overflow checks are disabled (default in release mode).

Examples

Basic usage:

#![feature(int_roundings)]
let a: i8 = 8;
let b = 3;

assert_eq!(a.div_floor(b), 2);
assert_eq!(a.div_floor(-b), -3);
assert_eq!((-a).div_floor(b), -3);
assert_eq!((-a).div_floor(-b), 2);

pub const fn div_ceil(self, rhs: i8) -> i8

🔬This is a nightly-only experimental API. (int_roundings #88581)

Calculates the quotient of self and rhs, rounding the result towards positive infinity.

Panics

This function will panic if rhs is zero.

Overflow behavior

On overflow, this function will panic if overflow checks are enabled (default in debug mode) and wrap if overflow checks are disabled (default in release mode).

Examples

Basic usage:

#![feature(int_roundings)]
let a: i8 = 8;
let b = 3;

assert_eq!(a.div_ceil(b), 3);
assert_eq!(a.div_ceil(-b), -2);
assert_eq!((-a).div_ceil(b), -2);
assert_eq!((-a).div_ceil(-b), 3);

pub const fn next_multiple_of(self, rhs: i8) -> i8

🔬This is a nightly-only experimental API. (int_roundings #88581)

If rhs is positive, calculates the smallest value greater than or equal to self that is a multiple of rhs. If rhs is negative, calculates the largest value less than or equal to self that is a multiple of rhs.

Panics

This function will panic if rhs is zero.

Overflow behavior

On overflow, this function will panic if overflow checks are enabled (default in debug mode) and wrap if overflow checks are disabled (default in release mode).

Examples

Basic usage:

#![feature(int_roundings)]
assert_eq!(16_i8.next_multiple_of(8), 16);
assert_eq!(23_i8.next_multiple_of(8), 24);
assert_eq!(16_i8.next_multiple_of(-8), 16);
assert_eq!(23_i8.next_multiple_of(-8), 16);
assert_eq!((-16_i8).next_multiple_of(8), -16);
assert_eq!((-23_i8).next_multiple_of(8), -16);
assert_eq!((-16_i8).next_multiple_of(-8), -16);
assert_eq!((-23_i8).next_multiple_of(-8), -24);

pub const fn checked_next_multiple_of(self, rhs: i8) -> Option<i8>

🔬This is a nightly-only experimental API. (int_roundings #88581)

If rhs is positive, calculates the smallest value greater than or equal to self that is a multiple of rhs. If rhs is negative, calculates the largest value less than or equal to self that is a multiple of rhs. Returns None if rhs is zero or the operation would result in overflow.

Examples

Basic usage:

#![feature(int_roundings)]
assert_eq!(16_i8.checked_next_multiple_of(8), Some(16));
assert_eq!(23_i8.checked_next_multiple_of(8), Some(24));
assert_eq!(16_i8.checked_next_multiple_of(-8), Some(16));
assert_eq!(23_i8.checked_next_multiple_of(-8), Some(16));
assert_eq!((-16_i8).checked_next_multiple_of(8), Some(-16));
assert_eq!((-23_i8).checked_next_multiple_of(8), Some(-16));
assert_eq!((-16_i8).checked_next_multiple_of(-8), Some(-16));
assert_eq!((-23_i8).checked_next_multiple_of(-8), Some(-24));
assert_eq!(1_i8.checked_next_multiple_of(0), None);
assert_eq!(i8::MAX.checked_next_multiple_of(2), None);

const: unstable · source

pub fn midpoint(self, rhs: i8) -> i8

🔬This is a nightly-only experimental API. (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)]
assert_eq!(0i8.midpoint(4), 2);
assert_eq!(0i8.midpoint(-1), -1);
assert_eq!((-1i8).midpoint(0), -1);

1.67.0 (const: 1.67.0) · source

pub const fn ilog(self, base: i8) -> u32

Returns the logarithm of the number with respect to an arbitrary base, rounded down.

This method might not be optimized owing to implementation details; ilog2 can produce results more efficiently for base 2, and ilog10 can produce results more efficiently for base 10.

Panics

This function will panic if self is less than or equal to zero, or if base is less than 2.

Examples

assert_eq!(5i8.ilog(5), 1);

1.67.0 (const: 1.67.0) · source

pub const fn ilog2(self) -> u32

Returns the base 2 logarithm of the number, rounded down.

Panics

This function will panic if self is less than or equal to zero.

Examples

assert_eq!(2i8.ilog2(), 1);

1.67.0 (const: 1.67.0) · source

pub const fn ilog10(self) -> u32

Returns the base 10 logarithm of the number, rounded down.

Panics

This function will panic if self is less than or equal to zero.

Example

assert_eq!(10i8.ilog10(), 1);

1.67.0 (const: 1.67.0) · source

pub const fn checked_ilog(self, base: i8) -> Option<u32>

Returns the logarithm of the number with respect to an arbitrary base, rounded down.

Returns None if the number is negative or zero, or if the base is not at least 2.

This method might not be optimized owing to implementation details; checked_ilog2 can produce results more efficiently for base 2, and checked_ilog10 can produce results more efficiently for base 10.

Examples

assert_eq!(5i8.checked_ilog(5), Some(1));

1.67.0 (const: 1.67.0) · source

pub const fn checked_ilog2(self) -> Option<u32>

Returns the base 2 logarithm of the number, rounded down.

Returns None if the number is negative or zero.

Examples

assert_eq!(2i8.checked_ilog2(), Some(1));

1.67.0 (const: 1.67.0) · source

pub const fn checked_ilog10(self) -> Option<u32>

Returns the base 10 logarithm of the number, rounded down.

Returns None if the number is negative or zero.

Example

assert_eq!(10i8.checked_ilog10(), Some(1));

const: 1.32.0 · source

pub const fn abs(self) -> i8

Computes the absolute value of self.

Overflow behavior

The absolute value of i8::MIN cannot be represented as an i8, and attempting to calculate it will cause an overflow. This means that code in debug mode will trigger a panic on this case and optimized code will return i8::MIN without a panic.

Examples

Basic usage:

assert_eq!(10i8.abs(), 10);
assert_eq!((-10i8).abs(), 10);

1.60.0 (const: 1.60.0) · source

pub const fn abs_diff(self, other: i8) -> u8

Computes the absolute difference between self and other.

This function always returns the correct answer without overflow or panics by returning an unsigned integer.

Examples

Basic usage:

assert_eq!(100i8.abs_diff(80), 20u8);
assert_eq!(100i8.abs_diff(110), 10u8);
assert_eq!((-100i8).abs_diff(80), 180u8);
assert_eq!((-100i8).abs_diff(-120), 20u8);
assert_eq!(i8::MIN.abs_diff(i8::MAX), u8::MAX);

const: 1.47.0 · source

pub const fn signum(self) -> i8

Returns a number representing sign of self.

0 if the number is zero
1 if the number is positive
-1 if the number is negative

Examples

Basic usage:

assert_eq!(10i8.signum(), 1);
assert_eq!(0i8.signum(), 0);
assert_eq!((-10i8).signum(), -1);

const: 1.32.0 · source

pub const fn is_positive(self) -> bool

Returns true if self is positive and false if the number is zero or negative.

Examples

Basic usage:

assert!(10i8.is_positive());
assert!(!(-10i8).is_positive());

const: 1.32.0 · source

pub const fn is_negative(self) -> bool

Returns true if self is negative and false if the number is zero or positive.

Examples

Basic usage:

assert!((-10i8).is_negative());
assert!(!10i8.is_negative());

1.32.0 (const: 1.44.0) · source

pub const fn to_be_bytes(self) -> [u8; 1]

Return the memory representation of this integer as a byte array in big-endian (network) byte order.

Examples

let bytes = 0x12i8.to_be_bytes();
assert_eq!(bytes, [0x12]);

1.32.0 (const: 1.44.0) · source

pub const fn to_le_bytes(self) -> [u8; 1]

Return the memory representation of this integer as a byte array in little-endian byte order.

Examples

let bytes = 0x12i8.to_le_bytes();
assert_eq!(bytes, [0x12]);

1.32.0 (const: 1.44.0) · source

pub const fn to_ne_bytes(self) -> [u8; 1]

Return the memory representation of this integer as a byte array in native byte order.

As the target platform’s native endianness is used, portable code should use to_be_bytes or to_le_bytes, as appropriate, instead.

Examples

let bytes = 0x12i8.to_ne_bytes();
assert_eq!(
    bytes,
    if cfg!(target_endian = "big") {
        [0x12]
    } else {
        [0x12]
    }
);

1.32.0 (const: 1.44.0) · source

pub const fn from_be_bytes(bytes: [u8; 1]) -> i8

Create an integer value from its representation as a byte array in big endian.

Examples

let value = i8::from_be_bytes([0x12]);
assert_eq!(value, 0x12);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_be_i8(input: &mut &[u8]) -> i8 {
    let (int_bytes, rest) = input.split_at(std::mem::size_of::<i8>());
    *input = rest;
    i8::from_be_bytes(int_bytes.try_into().unwrap())
}

1.32.0 (const: 1.44.0) · source

pub const fn from_le_bytes(bytes: [u8; 1]) -> i8

Create an integer value from its representation as a byte array in little endian.

Examples

let value = i8::from_le_bytes([0x12]);
assert_eq!(value, 0x12);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_le_i8(input: &mut &[u8]) -> i8 {
    let (int_bytes, rest) = input.split_at(std::mem::size_of::<i8>());
    *input = rest;
    i8::from_le_bytes(int_bytes.try_into().unwrap())
}

1.32.0 (const: 1.44.0) · source

pub const fn from_ne_bytes(bytes: [u8; 1]) -> i8

Create an integer value from its memory representation as a byte array in native endianness.

As the target platform’s native endianness is used, portable code likely wants to use from_be_bytes or from_le_bytes, as appropriate instead.

Examples

let value = i8::from_ne_bytes(if cfg!(target_endian = "big") {
    [0x12]
} else {
    [0x12]
});
assert_eq!(value, 0x12);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_ne_i8(input: &mut &[u8]) -> i8 {
    let (int_bytes, rest) = input.split_at(std::mem::size_of::<i8>());
    *input = rest;
    i8::from_ne_bytes(int_bytes.try_into().unwrap())
}

const: 1.32.0 · source

pub const fn min_value() -> i8

👎Deprecating in a future Rust version: replaced by the MIN associated constant on this type

New code should prefer to use i8::MIN instead.

Returns the smallest value that can be represented by this integer type.

const: 1.32.0 · source

pub const fn max_value() -> i8

👎Deprecating in a future Rust version: replaced by the MAX associated constant on this type

New code should prefer to use i8::MAX instead.

Returns the largest value that can be represented by this integer type.

type Output = i8

The resulting type after applying the / operator.

fn from(small: bool) -> i8

Converts a bool to a i8. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(i8::from(true), 1);
assert_eq!(i8::from(false), 0);

impl Hash for i8

fn hash<H>(&self, state: &mut H)where H: Hasher,

Feeds this value into the given Hasher. Read more

fn hash_slice<H>(data: &[i8], state: &mut H)where H: Hasher,

Feeds a slice of this type into the given Hasher. Read more

1.42.0 · source§

impl LowerExp for i8

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

Formats the value using the given formatter.

impl Ord for i8

fn cmp(&self, other: &i8) -> Ordering

This method returns an Ordering between self and other. Read more

1.21.0 · source§

fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values. Read more

1.21.0 · source§

fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values. Read more

1.50.0 · source§

fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval. Read more

impl PartialEq<i8> for i8

fn eq(&self, other: &i8) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &i8) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

The resulting type after applying the % operator.

Formats the value using the given formatter.

impl UpperHex for i8

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl TrustedStep for i8

fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

Performs the conversion.

impl<T, U> TryInto for Twhere U: TryFrom<T>,

§

type Error = >::Error

The type returned in the event of a conversion error.