Primitive Type i8 [−]
The 8-bit signed integer type.
Methods
impl i8
1.0.0fn min_value() -> i8
Returns the smallest value that can be represented by this integer type.
1.0.0fn max_value() -> i8
Returns the largest value that can be represented by this integer type.
1.0.0fn from_str_radix(src: &str, radix: u32) -> Result<i8, ParseIntError>
Converts a string slice in a given base to an integer.
Leading and trailing whitespace represent an error.
Examples
Basic usage:
fn main() { assert_eq!(u32::from_str_radix("A", 16), Ok(10)); }assert_eq!(u32::from_str_radix("A", 16), Ok(10));
1.0.0fn count_ones(self) -> u32
Returns the number of ones in the binary representation of self
.
Examples
Basic usage:
fn main() { let n = 0b01001100u8; assert_eq!(n.count_ones(), 3); }let n = 0b01001100u8; assert_eq!(n.count_ones(), 3);
1.0.0fn count_zeros(self) -> u32
Returns the number of zeros in the binary representation of self
.
Examples
Basic usage:
fn main() { let n = 0b01001100u8; assert_eq!(n.count_zeros(), 5); }let n = 0b01001100u8; assert_eq!(n.count_zeros(), 5);
1.0.0fn leading_zeros(self) -> u32
Returns the number of leading zeros in the binary representation
of self
.
Examples
Basic usage:
fn main() { let n = 0b0101000u16; assert_eq!(n.leading_zeros(), 10); }let n = 0b0101000u16; assert_eq!(n.leading_zeros(), 10);
1.0.0fn trailing_zeros(self) -> u32
Returns the number of trailing zeros in the binary representation
of self
.
Examples
Basic usage:
fn main() { let n = 0b0101000u16; assert_eq!(n.trailing_zeros(), 3); }let n = 0b0101000u16; assert_eq!(n.trailing_zeros(), 3);
1.0.0fn 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.
Examples
Basic usage:
fn main() { let n = 0x0123456789ABCDEFu64; let m = 0x3456789ABCDEF012u64; assert_eq!(n.rotate_left(12), m); }let n = 0x0123456789ABCDEFu64; let m = 0x3456789ABCDEF012u64; assert_eq!(n.rotate_left(12), m);
1.0.0fn 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.
Examples
Basic usage:
fn main() { let n = 0x0123456789ABCDEFu64; let m = 0xDEF0123456789ABCu64; assert_eq!(n.rotate_right(12), m); }let n = 0x0123456789ABCDEFu64; let m = 0xDEF0123456789ABCu64; assert_eq!(n.rotate_right(12), m);
1.0.0fn swap_bytes(self) -> i8
Reverses the byte order of the integer.
Examples
Basic usage:
fn main() { let n = 0x0123456789ABCDEFu64; let m = 0xEFCDAB8967452301u64; assert_eq!(n.swap_bytes(), m); }let n = 0x0123456789ABCDEFu64; let m = 0xEFCDAB8967452301u64; assert_eq!(n.swap_bytes(), m);
1.0.0fn 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.
Examples
Basic usage:
fn main() { let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "big") { assert_eq!(u64::from_be(n), n) } else { assert_eq!(u64::from_be(n), n.swap_bytes()) } }let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "big") { assert_eq!(u64::from_be(n), n) } else { assert_eq!(u64::from_be(n), n.swap_bytes()) }
1.0.0fn 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.
Examples
Basic usage:
fn main() { let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "little") { assert_eq!(u64::from_le(n), n) } else { assert_eq!(u64::from_le(n), n.swap_bytes()) } }let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "little") { assert_eq!(u64::from_le(n), n) } else { assert_eq!(u64::from_le(n), n.swap_bytes()) }
1.0.0fn 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.
Examples
Basic usage:
fn main() { let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "big") { assert_eq!(n.to_be(), n) } else { assert_eq!(n.to_be(), n.swap_bytes()) } }let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "big") { assert_eq!(n.to_be(), n) } else { assert_eq!(n.to_be(), n.swap_bytes()) }
1.0.0fn to_le(self) -> i8
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:
fn main() { let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "little") { assert_eq!(n.to_le(), n) } else { assert_eq!(n.to_le(), n.swap_bytes()) } }let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "little") { assert_eq!(n.to_le(), n) } else { assert_eq!(n.to_le(), n.swap_bytes()) }
1.0.0fn checked_add(self, other: i8) -> Option<i8>
Checked integer addition. Computes self + other
, returning None
if overflow occurred.
Examples
Basic usage:
fn main() { assert_eq!(5u16.checked_add(65530), Some(65535)); assert_eq!(6u16.checked_add(65530), None); }assert_eq!(5u16.checked_add(65530), Some(65535)); assert_eq!(6u16.checked_add(65530), None);
1.0.0fn checked_sub(self, other: i8) -> Option<i8>
Checked integer subtraction. Computes self - other
, returning
None
if underflow occurred.
Examples
Basic usage:
fn main() { assert_eq!((-127i8).checked_sub(1), Some(-128)); assert_eq!((-128i8).checked_sub(1), None); }assert_eq!((-127i8).checked_sub(1), Some(-128)); assert_eq!((-128i8).checked_sub(1), None);
1.0.0fn checked_mul(self, other: i8) -> Option<i8>
Checked integer multiplication. Computes self * other
, returning
None
if underflow or overflow occurred.
Examples
Basic usage:
fn main() { assert_eq!(5u8.checked_mul(51), Some(255)); assert_eq!(5u8.checked_mul(52), None); }assert_eq!(5u8.checked_mul(51), Some(255)); assert_eq!(5u8.checked_mul(52), None);
1.0.0fn checked_div(self, other: i8) -> Option<i8>
Checked integer division. Computes self / other
, returning None
if other == 0
or the operation results in underflow or overflow.
Examples
Basic usage:
fn main() { assert_eq!((-127i8).checked_div(-1), Some(127)); assert_eq!((-128i8).checked_div(-1), None); assert_eq!((1i8).checked_div(0), None); }assert_eq!((-127i8).checked_div(-1), Some(127)); assert_eq!((-128i8).checked_div(-1), None); assert_eq!((1i8).checked_div(0), None);
1.7.0fn checked_rem(self, other: i8) -> Option<i8>
Checked integer remainder. Computes self % other
, returning None
if other == 0
or the operation results in underflow or overflow.
Examples
Basic usage:
fn main() { use std::i32; assert_eq!(5i32.checked_rem(2), Some(1)); assert_eq!(5i32.checked_rem(0), None); assert_eq!(i32::MIN.checked_rem(-1), None); }use std::i32; assert_eq!(5i32.checked_rem(2), Some(1)); assert_eq!(5i32.checked_rem(0), None); assert_eq!(i32::MIN.checked_rem(-1), None);
1.7.0fn checked_neg(self) -> Option<i8>
Checked negation. Computes -self
, returning None
if self == MIN
.
Examples
Basic usage:
fn main() { use std::i32; assert_eq!(5i32.checked_neg(), Some(-5)); assert_eq!(i32::MIN.checked_neg(), None); }use std::i32; assert_eq!(5i32.checked_neg(), Some(-5)); assert_eq!(i32::MIN.checked_neg(), None);
1.7.0fn 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
.
Examples
Basic usage:
fn main() { assert_eq!(0x10i32.checked_shl(4), Some(0x100)); assert_eq!(0x10i32.checked_shl(33), None); }assert_eq!(0x10i32.checked_shl(4), Some(0x100)); assert_eq!(0x10i32.checked_shl(33), None);
1.7.0fn 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
.
Examples
Basic usage:
fn main() { assert_eq!(0x10i32.checked_shr(4), Some(0x1)); assert_eq!(0x10i32.checked_shr(33), None); }assert_eq!(0x10i32.checked_shr(4), Some(0x1)); assert_eq!(0x10i32.checked_shr(33), None);
1.0.0fn saturating_add(self, other: i8) -> i8
Saturating integer addition. Computes self + other
, saturating at
the numeric bounds instead of overflowing.
Examples
Basic usage:
fn main() { assert_eq!(100i8.saturating_add(1), 101); assert_eq!(100i8.saturating_add(127), 127); }assert_eq!(100i8.saturating_add(1), 101); assert_eq!(100i8.saturating_add(127), 127);
1.0.0fn saturating_sub(self, other: i8) -> i8
Saturating integer subtraction. Computes self - other
, saturating
at the numeric bounds instead of overflowing.
Examples
Basic usage:
fn main() { assert_eq!(100i8.saturating_sub(127), -27); assert_eq!((-100i8).saturating_sub(127), -128); }assert_eq!(100i8.saturating_sub(127), -27); assert_eq!((-100i8).saturating_sub(127), -128);
1.7.0fn saturating_mul(self, other: i8) -> i8
Saturating integer multiplication. Computes self * other
,
saturating at the numeric bounds instead of overflowing.
Examples
Basic usage:
fn main() { use std::i32; assert_eq!(100i32.saturating_mul(127), 12700); assert_eq!((1i32 << 23).saturating_mul(1 << 23), i32::MAX); assert_eq!((-1i32 << 23).saturating_mul(1 << 23), i32::MIN); }use std::i32; assert_eq!(100i32.saturating_mul(127), 12700); assert_eq!((1i32 << 23).saturating_mul(1 << 23), i32::MAX); assert_eq!((-1i32 << 23).saturating_mul(1 << 23), i32::MIN);
1.0.0fn wrapping_add(self, rhs: i8) -> i8
Wrapping (modular) addition. Computes self + other
,
wrapping around at the boundary of the type.
Examples
Basic usage:
fn main() { assert_eq!(100i8.wrapping_add(27), 127); assert_eq!(100i8.wrapping_add(127), -29); }assert_eq!(100i8.wrapping_add(27), 127); assert_eq!(100i8.wrapping_add(127), -29);
1.0.0fn wrapping_sub(self, rhs: i8) -> i8
Wrapping (modular) subtraction. Computes self - other
,
wrapping around at the boundary of the type.
Examples
Basic usage:
fn main() { assert_eq!(0i8.wrapping_sub(127), -127); assert_eq!((-2i8).wrapping_sub(127), 127); }assert_eq!(0i8.wrapping_sub(127), -127); assert_eq!((-2i8).wrapping_sub(127), 127);
1.0.0fn wrapping_mul(self, rhs: i8) -> i8
Wrapping (modular) multiplication. Computes self * other
, wrapping around at the boundary of the type.
Examples
Basic usage:
fn main() { assert_eq!(10i8.wrapping_mul(12), 120); assert_eq!(11i8.wrapping_mul(12), -124); }assert_eq!(10i8.wrapping_mul(12), 120); assert_eq!(11i8.wrapping_mul(12), -124);
1.2.0fn wrapping_div(self, rhs: i8) -> i8
Wrapping (modular) division. Computes self / other
,
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:
fn main() { assert_eq!(100u8.wrapping_div(10), 10); assert_eq!((-128i8).wrapping_div(-1), -128); }assert_eq!(100u8.wrapping_div(10), 10); assert_eq!((-128i8).wrapping_div(-1), -128);
1.2.0fn wrapping_rem(self, rhs: i8) -> i8
Wrapping (modular) remainder. Computes self % other
,
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:
fn main() { assert_eq!(100i8.wrapping_rem(10), 0); assert_eq!((-128i8).wrapping_rem(-1), 0); }assert_eq!(100i8.wrapping_rem(10), 0); assert_eq!((-128i8).wrapping_rem(-1), 0);
1.2.0fn 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:
fn main() { assert_eq!(100i8.wrapping_neg(), -100); assert_eq!((-128i8).wrapping_neg(), -128); }assert_eq!(100i8.wrapping_neg(), -100); assert_eq!((-128i8).wrapping_neg(), -128);
1.2.0fn 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:
fn main() { assert_eq!(1u8.wrapping_shl(7), 128); assert_eq!(1u8.wrapping_shl(8), 1); }assert_eq!(1u8.wrapping_shl(7), 128); assert_eq!(1u8.wrapping_shl(8), 1);
1.2.0fn 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:
fn main() { assert_eq!(128u8.wrapping_shr(7), 1); assert_eq!(128u8.wrapping_shr(8), 128); }assert_eq!(128u8.wrapping_shr(7), 1); assert_eq!(128u8.wrapping_shr(8), 128);
1.7.0fn 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
fn main() { use std::i32; assert_eq!(5i32.overflowing_add(2), (7, false)); assert_eq!(i32::MAX.overflowing_add(1), (i32::MIN, true)); }use std::i32; assert_eq!(5i32.overflowing_add(2), (7, false)); assert_eq!(i32::MAX.overflowing_add(1), (i32::MIN, true));
1.7.0fn 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
fn main() { use std::i32; assert_eq!(5i32.overflowing_sub(2), (3, false)); assert_eq!(i32::MIN.overflowing_sub(1), (i32::MAX, true)); }use std::i32; assert_eq!(5i32.overflowing_sub(2), (3, false)); assert_eq!(i32::MIN.overflowing_sub(1), (i32::MAX, true));
1.7.0fn 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
fn main() { assert_eq!(5i32.overflowing_mul(2), (10, false)); assert_eq!(1_000_000_000i32.overflowing_mul(10), (1410065408, true)); }assert_eq!(5i32.overflowing_mul(2), (10, false)); assert_eq!(1_000_000_000i32.overflowing_mul(10), (1410065408, true));
1.7.0fn 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
fn main() { use std::i32; assert_eq!(5i32.overflowing_div(2), (2, false)); assert_eq!(i32::MIN.overflowing_div(-1), (i32::MIN, true)); }use std::i32; assert_eq!(5i32.overflowing_div(2), (2, false)); assert_eq!(i32::MIN.overflowing_div(-1), (i32::MIN, true));
1.7.0fn 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
fn main() { use std::i32; assert_eq!(5i32.overflowing_rem(2), (1, false)); assert_eq!(i32::MIN.overflowing_rem(-1), (0, true)); }use std::i32; assert_eq!(5i32.overflowing_rem(2), (1, false)); assert_eq!(i32::MIN.overflowing_rem(-1), (0, true));
1.7.0fn 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
fn main() { use std::i32; assert_eq!(2i32.overflowing_neg(), (-2, false)); assert_eq!(i32::MIN.overflowing_neg(), (i32::MIN, true)); }use std::i32; assert_eq!(2i32.overflowing_neg(), (-2, false)); assert_eq!(i32::MIN.overflowing_neg(), (i32::MIN, true));
1.7.0fn 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
fn main() { assert_eq!(0x10i32.overflowing_shl(4), (0x100, false)); assert_eq!(0x10i32.overflowing_shl(36), (0x100, true)); }assert_eq!(0x10i32.overflowing_shl(4), (0x100, false)); assert_eq!(0x10i32.overflowing_shl(36), (0x100, true));
1.7.0fn 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
fn main() { assert_eq!(0x10i32.overflowing_shr(4), (0x1, false)); assert_eq!(0x10i32.overflowing_shr(36), (0x1, true)); }assert_eq!(0x10i32.overflowing_shr(4), (0x1, false)); assert_eq!(0x10i32.overflowing_shr(36), (0x1, true));
1.0.0fn pow(self, exp: u32) -> i8
Raises self to the power of exp
, using exponentiation by squaring.
Examples
Basic usage:
fn main() { let x: i32 = 2; // or any other integer type assert_eq!(x.pow(4), 16); }let x: i32 = 2; // or any other integer type assert_eq!(x.pow(4), 16);
1.0.0fn abs(self) -> i8
Computes the absolute value of self
.
Overflow behavior
The absolute value of i32::min_value()
cannot be represented as an
i32
, 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 i32::min_value()
without a panic.
Examples
Basic usage:
fn main() { assert_eq!(10i8.abs(), 10); assert_eq!((-10i8).abs(), 10); }assert_eq!(10i8.abs(), 10); assert_eq!((-10i8).abs(), 10);
1.0.0fn signum(self) -> i8
Returns a number representing sign of self
.
0
if the number is zero1
if the number is positive-1
if the number is negative
Examples
Basic usage:
fn main() { assert_eq!(10i8.signum(), 1); assert_eq!(0i8.signum(), 0); assert_eq!((-10i8).signum(), -1); }assert_eq!(10i8.signum(), 1); assert_eq!(0i8.signum(), 0); assert_eq!((-10i8).signum(), -1);
1.0.0fn is_positive(self) -> bool
Returns true
if self
is positive and false
if the number
is zero or negative.
Examples
Basic usage:
fn main() { assert!(10i8.is_positive()); assert!(!(-10i8).is_positive()); }assert!(10i8.is_positive()); assert!(!(-10i8).is_positive());
1.0.0fn is_negative(self) -> bool
Returns true
if self
is negative and false
if the number
is zero or positive.
Examples
Basic usage:
fn main() { assert!((-10i8).is_negative()); assert!(!10i8.is_negative()); }assert!((-10i8).is_negative()); assert!(!10i8.is_negative());
Trait Implementations
impl OverflowingOps for i8
fn overflowing_add(self, rhs: i8) -> (i8, bool)
fn overflowing_sub(self, rhs: i8) -> (i8, bool)
fn overflowing_mul(self, rhs: i8) -> (i8, bool)
fn overflowing_div(self, rhs: i8) -> (i8, bool)
fn overflowing_rem(self, rhs: i8) -> (i8, bool)
fn overflowing_shl(self, rhs: u32) -> (i8, bool)
fn overflowing_shr(self, rhs: u32) -> (i8, bool)
fn overflowing_neg(self) -> (i8, bool)
impl Zero for i8
impl One for i8
impl FromStr for i8
1.0.0
type Err = ParseIntError
fn from_str(src: &str) -> Result<i8, ParseIntError>
impl Zeroable for i8
impl Add<i8> for i8
1.0.0
impl<'a> Add<i8> for &'a i8
1.0.0
impl<'a> Add<&'a i8> for i8
1.0.0
impl<'a, 'b> Add<&'a i8> for &'b i8
1.0.0
impl Sub<i8> for i8
1.0.0
impl<'a> Sub<i8> for &'a i8
1.0.0
impl<'a> Sub<&'a i8> for i8
1.0.0
impl<'a, 'b> Sub<&'a i8> for &'b i8
1.0.0
impl Mul<i8> for i8
1.0.0
impl<'a> Mul<i8> for &'a i8
1.0.0
impl<'a> Mul<&'a i8> for i8
1.0.0
impl<'a, 'b> Mul<&'a i8> for &'b i8
1.0.0
impl Div<i8> for i8
1.0.0
This operation rounds towards zero, truncating any fractional part of the exact result.
impl<'a> Div<i8> for &'a i8
1.0.0
impl<'a> Div<&'a i8> for i8
1.0.0
impl<'a, 'b> Div<&'a i8> for &'b i8
1.0.0
impl Rem<i8> for i8
1.0.0
This operation satisfies n % d == n - (n / d) * d
. The
result has the same sign as the left operand.