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Primitive Type i8

The 8-bit signed integer type.

See also the std::i8 module.

However, please note that examples are shared between primitive integer types. So it's normal if you see usage of types like i64 in there.

Methods

`impl i8` [src]

`fn min_value() -> i8`

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

Examples

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

`fn max_value() -> i8`

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

Examples

assert_eq!(i8::max_value(), 127);

`fn 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:

assert_eq!(i32::from_str_radix("A", 16), Ok(10));

`fn count_ones(self) -> u32`

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

Examples

Basic usage:

let n = -0b1000_0000i8;

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

`fn count_zeros(self) -> u32`

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

Examples

Basic usage:

let n = -0b1000_0000i8;

assert_eq!(n.count_zeros(), 7);

`fn leading_zeros(self) -> u32`

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

Examples

Basic usage:

let n = -1i16;

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

`fn trailing_zeros(self) -> u32`

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

Examples

Basic usage:

let n = -4i8;

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

`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 <<!

Examples

Basic usage:

let n = 0x0123456789ABCDEFi64;
let m = -0x76543210FEDCBA99i64;

assert_eq!(n.rotate_left(32), m);

`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 >>!

Examples

Basic usage:

let n = 0x0123456789ABCDEFi64;
let m = -0xFEDCBA987654322i64;

assert_eq!(n.rotate_right(4), m);

`fn swap_bytes(self) -> i8`

Reverses the byte order of the integer.

Examples

Basic usage:

let n =  0x0123456789ABCDEFi64;
let m = -0x1032547698BADCFFi64;

assert_eq!(n.swap_bytes(), m);

`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.

Examples

Basic usage:

let n = 0x0123456789ABCDEFi64;

if cfg!(target_endian = "big") {
    assert_eq!(i64::from_be(n), n)
} else {
    assert_eq!(i64::from_be(n), n.swap_bytes())
}

`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.

Examples

Basic usage:

let n = 0x0123456789ABCDEFi64;

if cfg!(target_endian = "little") {
    assert_eq!(i64::from_le(n), n)
} else {
    assert_eq!(i64::from_le(n), n.swap_bytes())
}

`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.

Examples

Basic usage:

let n = 0x0123456789ABCDEFi64;

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

`fn 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:

let n = 0x0123456789ABCDEFi64;

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

`fn checked_add(self, other: i8) -> Option<i8>`

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

Examples

Basic usage:

assert_eq!(7i16.checked_add(32760), Some(32767));
assert_eq!(8i16.checked_add(32760), None);

`fn checked_sub(self, other: i8) -> Option<i8>`

Checked integer subtraction. Computes self - other, returning None if underflow occurred.

Examples

Basic usage:

assert_eq!((-127i8).checked_sub(1), Some(-128));
assert_eq!((-128i8).checked_sub(1), None);

`fn checked_mul(self, other: i8) -> Option<i8>`

Checked integer multiplication. Computes self * other, returning None if underflow or overflow occurred.

Examples

Basic usage:

assert_eq!(6i8.checked_mul(21), Some(126));
assert_eq!(6i8.checked_mul(22), None);

`fn 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:

assert_eq!((-127i8).checked_div(-1), Some(127));
assert_eq!((-128i8).checked_div(-1), None);
assert_eq!((1i8).checked_div(0), None);

`fn checked_rem(self, other: i8) -> Option<i8>`
1.7.0

Checked integer remainder. Computes self % other, returning None if other == 0 or the operation results in underflow or overflow.

Examples

Basic usage:

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);

`fn checked_neg(self) -> Option<i8>`
1.7.0

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

Examples

Basic usage:

use std::i32;

assert_eq!(5i32.checked_neg(), Some(-5));
assert_eq!(i32::MIN.checked_neg(), None);

`fn checked_shl(self, rhs: u32) -> Option<i8>`
1.7.0

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!(0x10i32.checked_shl(4), Some(0x100));
assert_eq!(0x10i32.checked_shl(33), None);

`fn checked_shr(self, rhs: u32) -> Option<i8>`
1.7.0

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!(0x10i32.checked_shr(4), Some(0x1));
assert_eq!(0x10i32.checked_shr(33), None);

`fn checked_abs(self) -> Option<i8>`
1.13.0

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

Examples

Basic usage:

use std::i32;

assert_eq!((-5i32).checked_abs(), Some(5));
assert_eq!(i32::MIN.checked_abs(), None);

`fn saturating_add(self, other: i8) -> i8`

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

Examples

Basic usage:

assert_eq!(100i8.saturating_add(1), 101);
assert_eq!(100i8.saturating_add(127), 127);

`fn saturating_sub(self, other: i8) -> i8`

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

Examples

Basic usage:

assert_eq!(100i8.saturating_sub(127), -27);
assert_eq!((-100i8).saturating_sub(127), -128);

`fn saturating_mul(self, other: i8) -> i8`
1.7.0

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

Examples

Basic usage:

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);

`fn wrapping_add(self, rhs: i8) -> i8`

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

Examples

Basic usage:

assert_eq!(100i8.wrapping_add(27), 127);
assert_eq!(100i8.wrapping_add(127), -29);

`fn wrapping_sub(self, rhs: i8) -> i8`

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

Examples

Basic usage:

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

`fn wrapping_mul(self, rhs: i8) -> i8`

Wrapping (modular) multiplication. Computes self * other, 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);

`fn wrapping_div(self, rhs: i8) -> i8`
1.2.0

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:

assert_eq!(100u8.wrapping_div(10), 10);
assert_eq!((-128i8).wrapping_div(-1), -128);

`fn wrapping_rem(self, rhs: i8) -> i8`
1.2.0

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:

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

`fn wrapping_neg(self) -> i8`
1.2.0

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!((-128i8).wrapping_neg(), -128);

`fn wrapping_shl(self, rhs: u32) -> i8`
1.2.0

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(8), -1);

`fn wrapping_shr(self, rhs: u32) -> i8`
1.2.0

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!((-128i8).wrapping_shr(8), -128);

`fn wrapping_abs(self) -> i8`
1.13.0

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

`fn overflowing_add(self, rhs: i8) -> (i8, bool)`
1.7.0

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

use std::i32;

assert_eq!(5i32.overflowing_add(2), (7, false));
assert_eq!(i32::MAX.overflowing_add(1), (i32::MIN, true));

`fn overflowing_sub(self, rhs: i8) -> (i8, bool)`
1.7.0

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

use std::i32;

assert_eq!(5i32.overflowing_sub(2), (3, false));
assert_eq!(i32::MIN.overflowing_sub(1), (i32::MAX, true));

`fn overflowing_mul(self, rhs: i8) -> (i8, bool)`
1.7.0

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!(5i32.overflowing_mul(2), (10, false));
assert_eq!(1_000_000_000i32.overflowing_mul(10), (1410065408, true));

`fn overflowing_div(self, rhs: i8) -> (i8, bool)`
1.7.0

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

use std::i32;

assert_eq!(5i32.overflowing_div(2), (2, false));
assert_eq!(i32::MIN.overflowing_div(-1), (i32::MIN, true));

`fn overflowing_rem(self, rhs: i8) -> (i8, bool)`
1.7.0

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

use std::i32;

assert_eq!(5i32.overflowing_rem(2), (1, false));
assert_eq!(i32::MIN.overflowing_rem(-1), (0, true));

`fn overflowing_neg(self) -> (i8, bool)`
1.7.0

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

use std::i32;

assert_eq!(2i32.overflowing_neg(), (-2, false));
assert_eq!(i32::MIN.overflowing_neg(), (i32::MIN, true));

`fn overflowing_shl(self, rhs: u32) -> (i8, bool)`
1.7.0

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!(0x10i32.overflowing_shl(4), (0x100, false));
assert_eq!(0x10i32.overflowing_shl(36), (0x100, true));

`fn overflowing_shr(self, rhs: u32) -> (i8, bool)`
1.7.0

Shifts self right by rhs bits.

Examples

Basic usage

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

`fn overflowing_abs(self) -> (i8, bool)`
1.13.0

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. 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!(10i8.overflowing_abs(), (10,false));
assert_eq!((-10i8).overflowing_abs(), (10,false));
assert_eq!((-128i8).overflowing_abs(), (-128,true));

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

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

Examples

Basic usage:

let x: i32 = 2; // or any other integer type

assert_eq!(x.pow(4), 16);

`fn 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:

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

`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);

`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());

`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());

Trait Implementations

`impl PartialEq<i8> for i8` [src]

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

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