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

Examples

Basic usage:

assert_eq!(i8::MIN, -128);

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

Examples

Basic usage:

assert_eq!(i8::MAX, 127);

The size of this integer type in bits.

Examples

assert_eq!(i8::BITS, 8);

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.

Examples

Basic usage:

assert_eq!(i8::from_str_radix("A", 16), Ok(10));

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

Examples

Basic usage:

let n = 0b100_0000i8;

assert_eq!(n.count_ones(), 1);

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

Examples

Basic usage:

assert_eq!(i8::MAX.count_zeros(), 1);

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.

Examples

Basic usage:

let n = -1i8;

assert_eq!(n.leading_zeros(), 0);

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

Examples

Basic usage:

let n = -4i8;

assert_eq!(n.trailing_zeros(), 2);

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

Examples

Basic usage:

let n = -1i8;

assert_eq!(n.leading_ones(), 8);

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

Examples

Basic usage:

let n = 3i8;

assert_eq!(n.trailing_ones(), 2);

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!

Examples

Basic usage:

let n = -0x7ei8;
let m = 0xa;

assert_eq!(n.rotate_left(2), m);

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!

Examples

Basic usage:

let n = 0xai8;
let m = -0x7e;

assert_eq!(n.rotate_right(2), m);

Reverses the byte order of the integer.

Examples

Basic usage:

let n = 0x12i8;

let m = n.swap_bytes();

assert_eq!(m, 0x12);

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.

Examples

Basic usage:

let n = 0x12i8;
let m = n.reverse_bits();

assert_eq!(m, 0x48);
assert_eq!(0, 0i8.reverse_bits());

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.

Examples

Basic usage:

let n = 0x1Ai8;

if cfg!(target_endian = "big") {
    assert_eq!(i8::from_be(n), n)
} else {
    assert_eq!(i8::from_be(n), n.swap_bytes())
}

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.

Examples

Basic usage:

let n = 0x1Ai8;

if cfg!(target_endian = "little") {
    assert_eq!(i8::from_le(n), n)
} else {
    assert_eq!(i8::from_le(n), n.swap_bytes())
}

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.

Examples

Basic usage:

let n = 0x1Ai8;

if cfg!(target_endian = "big") {
    assert_eq!(n.to_be(), n)
} else {
    assert_eq!(n.to_be(), n.swap_bytes())
}

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

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

Examples

Basic usage:

let n = 0x1Ai8;

if cfg!(target_endian = "little") {
    assert_eq!(n.to_le(), n)
} else {
    assert_eq!(n.to_le(), n.swap_bytes())
}

Checked integer addition. Computes self + rhs, returning None if overflow occurred.

Examples

Basic usage:

assert_eq!((i8::MAX - 2).checked_add(1), Some(i8::MAX - 1));
assert_eq!((i8::MAX - 2).checked_add(3), None);

Unchecked integer addition. Computes self + rhs, assuming overflow cannot occur.

Safety

This results in undefined behavior when self + rhs > i8::MAX or self + rhs < i8::MIN, i.e. when checked_add would return None.

Checked addition with an unsigned integer. Computes self + rhs, returning None if overflow occurred.

Examples

Basic usage:

assert_eq!(1i8.checked_add_unsigned(2), Some(3));
assert_eq!((i8::MAX - 2).checked_add_unsigned(3), None);

Checked integer subtraction. Computes self - rhs, returning None if overflow occurred.

Examples

Basic usage:

assert_eq!((i8::MIN + 2).checked_sub(1), Some(i8::MIN + 1));
assert_eq!((i8::MIN + 2).checked_sub(3), None);

Unchecked integer subtraction. Computes self - rhs, assuming overflow cannot occur.

Safety

This results in undefined behavior when self - rhs > i8::MAX or self - rhs < i8::MIN, i.e. when checked_sub would return None.

Checked subtraction with an unsigned integer. Computes self - rhs, returning None if overflow occurred.

Examples

Basic usage:

assert_eq!(1i8.checked_sub_unsigned(2), Some(-1));
assert_eq!((i8::MIN + 2).checked_sub_unsigned(3), None);

Checked integer multiplication. Computes self * rhs, returning None if overflow occurred.

Examples

Basic usage:

assert_eq!(i8::MAX.checked_mul(1), Some(i8::MAX));
assert_eq!(i8::MAX.checked_mul(2), None);

Unchecked integer multiplication. Computes self * rhs, assuming overflow cannot occur.

Safety

This results in undefined behavior when self * rhs > i8::MAX or self * rhs < i8::MIN, i.e. when checked_mul would return None.

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

Examples

Basic usage:

assert_eq!((i8::MIN + 1).checked_div(-1), Some(127));
assert_eq!(i8::MIN.checked_div(-1), None);
assert_eq!((1i8).checked_div(0), None);

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

Examples

Basic usage:

assert_eq!((i8::MIN + 1).checked_div_euclid(-1), Some(127));
assert_eq!(i8::MIN.checked_div_euclid(-1), None);
assert_eq!((1i8).checked_div_euclid(0), None);

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

Examples

Basic usage:

assert_eq!(5i8.checked_rem(2), Some(1));
assert_eq!(5i8.checked_rem(0), None);
assert_eq!(i8::MIN.checked_rem(-1), None);

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

Examples

Basic usage:

assert_eq!(5i8.checked_rem_euclid(2), Some(1));
assert_eq!(5i8.checked_rem_euclid(0), None);
assert_eq!(i8::MIN.checked_rem_euclid(-1), None);

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

Examples

Basic usage:

assert_eq!(5i8.checked_neg(), Some(-5));
assert_eq!(i8::MIN.checked_neg(), None);

Unchecked negation. Computes -self, assuming overflow cannot occur.

Safety

This results in undefined behavior when self == i8::MIN, i.e. when checked_neg would return None.

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

Examples

Basic usage:

assert_eq!(0x1i8.checked_shl(4), Some(0x10));
assert_eq!(0x1i8.checked_shl(129), None);

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.

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

Examples

Basic usage:

assert_eq!(0x10i8.checked_shr(4), Some(0x1));
assert_eq!(0x10i8.checked_shr(128), None);

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.

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

Examples

Basic usage:

assert_eq!((-5i8).checked_abs(), Some(5));
assert_eq!(i8::MIN.checked_abs(), None);

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

Examples

Basic usage:

assert_eq!(8i8.checked_pow(2), Some(64));
assert_eq!(i8::MAX.checked_pow(2), None);

Returns the square root of the number, rounded down.

Returns None if self is negative.

Examples

Basic usage:

#![feature(isqrt)]
assert_eq!(10i8.checked_isqrt(), Some(3));

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

Examples

Basic usage:

assert_eq!(100i8.saturating_add(1), 101);
assert_eq!(i8::MAX.saturating_add(100), i8::MAX);
assert_eq!(i8::MIN.saturating_add(-1), i8::MIN);

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

Examples

Basic usage:

assert_eq!(1i8.saturating_add_unsigned(2), 3);
assert_eq!(i8::MAX.saturating_add_unsigned(100), i8::MAX);

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

Examples

Basic usage:

assert_eq!(100i8.saturating_sub(127), -27);
assert_eq!(i8::MIN.saturating_sub(100), i8::MIN);
assert_eq!(i8::MAX.saturating_sub(-1), i8::MAX);

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

Examples

Basic usage:

assert_eq!(100i8.saturating_sub_unsigned(127), -27);
assert_eq!(i8::MIN.saturating_sub_unsigned(100), i8::MIN);

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

Examples

Basic usage:

assert_eq!(100i8.saturating_neg(), -100);
assert_eq!((-100i8).saturating_neg(), 100);
assert_eq!(i8::MIN.saturating_neg(), i8::MAX);
assert_eq!(i8::MAX.saturating_neg(), i8::MIN + 1);

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

Examples

Basic usage:

assert_eq!(100i8.saturating_abs(), 100);
assert_eq!((-100i8).saturating_abs(), 100);
assert_eq!(i8::MIN.saturating_abs(), i8::MAX);
assert_eq!((i8::MIN + 1).saturating_abs(), i8::MAX);

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

Examples

Basic usage:

assert_eq!(10i8.saturating_mul(12), 120);
assert_eq!(i8::MAX.saturating_mul(10), i8::MAX);
assert_eq!(i8::MIN.saturating_mul(10), i8::MIN);

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

Examples

Basic usage:

assert_eq!(5i8.saturating_div(2), 2);
assert_eq!(i8::MAX.saturating_div(-1), i8::MIN + 1);
assert_eq!(i8::MIN.saturating_div(-1), i8::MAX);

let _ = 1i8.saturating_div(0);

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

Examples

Basic usage:

assert_eq!((-4i8).saturating_pow(3), -64);
assert_eq!(i8::MIN.saturating_pow(2), i8::MAX);
assert_eq!(i8::MIN.saturating_pow(3), i8::MIN);

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

Examples

Basic usage:

assert_eq!(100i8.wrapping_add(27), 127);
assert_eq!(i8::MAX.wrapping_add(2), i8::MIN + 1);

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

Examples

Basic usage:

assert_eq!(100i8.wrapping_add_unsigned(27), 127);
assert_eq!(i8::MAX.wrapping_add_unsigned(2), i8::MIN + 1);

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

Examples

Basic usage:

assert_eq!(0i8.wrapping_sub(127), -127);
assert_eq!((-2i8).wrapping_sub(i8::MAX), i8::MAX);

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

Examples

Basic usage:

assert_eq!(0i8.wrapping_sub_unsigned(127), -127);
assert_eq!((-2i8).wrapping_sub_unsigned(u8::MAX), -1);

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

Examples

Basic usage:

assert_eq!(10i8.wrapping_mul(12), 120);
assert_eq!(11i8.wrapping_mul(12), -124);

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);

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);

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);

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);

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);

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);

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);

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);

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);

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);

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));

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));

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));

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));

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));

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));

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));

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));

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));

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));

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));

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));

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));

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));

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));

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));

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);

Returns the square root of the number, rounded down.

Panics

This function will panic if self is negative.

Examples

Basic usage:

#![feature(isqrt)]
assert_eq!(10i8.isqrt(), 3);

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

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);

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);

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);

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);

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);

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);

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);

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);

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);

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));

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));

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));

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);

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);

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);

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());

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());

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]);

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]);

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]
    }
);

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())
}

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())
}

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())
}

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

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

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

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

Returns the default value of 0

Converts a NonZeroI8 into an 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);

Converts an i8 into an AtomicI8.

Converts i8 to f32 losslessly.

Converts i8 to f64 losslessly.

Converts i8 to i128 losslessly.

Converts i8 to i16 losslessly.

Converts i8 to i32 losslessly.

Converts i8 to i64 losslessly.

Converts i8 to isize losslessly.