# Primitive Type i81.0.0[−]

## Expand description

The 8-bit signed integer type.

## Implementations

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));`

Run## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

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

#85122)

niche optimization path

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`

.

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

#85122)

niche optimization path

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

#85122)

niche optimization path

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`

.

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

#85122)

niche optimization path

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

#85122)

niche optimization path

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 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);
```

Run## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

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

#85122)

niche optimization path

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`

.

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

#85122)

niche optimization path

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

#85122)

niche optimization path

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`

.

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);
```

RunSaturating 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);
```

RunWrapping (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);
```

RunWrapping 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);
```

RunWrapping (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);
```

RunWrapping 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);
```

RunWrapping (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);
```

RunPanic-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);
```

RunPanic-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);
```

RunWrapping (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);
```

RunCalculates `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));
```

RunCalculates `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));
```

RunCalculates 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));
```

RunCalculates 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));
```

RunCalculates 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));
```

RunCalculates 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));
```

RunOverflowing 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));
```

RunNegates 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));
```

RunShifts 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));
```

RunShifts 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));
```

RunComputes 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));
```

RunCalculates 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
```

RunCalculates 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);
```

RunReturns the logarithm of the number with respect to an arbitrary base.

This method might not be optimized owing to implementation details;
`log2`

can produce results more efficiently for base 2, and `log10`

can produce results more efficiently for base 10.

# Panics

When the number is zero, or if the base is not at least 2; it panics in debug mode and the return value is wrapped to 0 in release mode (the only situation in which the method can return 0).

# Examples

```
#![feature(int_log)]
assert_eq!(5i8.log(5), 1);
```

RunReturns the logarithm of the number with respect to an arbitrary base.

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_log2`

can produce results more efficiently for base 2, and
`checked_log10`

can produce results more efficiently for base 10.

# Examples

```
#![feature(int_log)]
assert_eq!(5i8.checked_log(5), Some(1));
```

RunComputes 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);
```

RunReturn 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]
}
);
```

RunCreate 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);
```

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

```
use std::convert::TryInto;
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())
}
```

RunCreate 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);
```

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

```
use std::convert::TryInto;
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())
}
```

RunCreate 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);
```

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

```
use std::convert::TryInto;
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())
}
```

Run## 👎 Deprecating in a future Rust version: replaced by the `MIN`

associated constant on this type

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.

## Trait Implementations

Performs the `+=`

operation. Read more

Performs the `+=`

operation. Read more

Performs the `&=`

operation. Read more

Performs the `&=`

operation. Read more

Performs the `|=`

operation. Read more

Performs the `|=`

operation. Read more

Performs the `^=`

operation. Read more

Performs the `^=`

operation. Read more

This operation rounds towards zero, truncating any fractional part of the exact result.

# Panics

This operation will panic if `other == 0`

or the division results in overflow.

Performs the `/=`

operation. Read more

Performs the `/=`

operation. Read more

#### type Err = ParseIntError

#### type Err = ParseIntError

The associated error which can be returned from parsing.

Performs the `*=`

operation. Read more

Performs the `*=`

operation. Read more

This method returns an ordering between `self`

and `other`

values if one exists. Read more

This method tests less than (for `self`

and `other`

) and is used by the `<`

operator. Read more

This method tests less than or equal to (for `self`

and `other`

) and is used by the `<=`

operator. Read more

This method tests greater than or equal to (for `self`

and `other`

) and is used by the `>=`

operator. Read more

This operation satisfies `n % d == n - (n / d) * d`

. The
result has the same sign as the left operand.

# Panics

This operation will panic if `other == 0`

or if `self / other`

results in overflow.

Performs the `%=`

operation. Read more

Performs the `%=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the value that would be obtained by taking the *successor*
of `self`

`count`

times. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the value that would be obtained by taking the *predecessor*
of `self`

`count`

times. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the value that would be obtained by taking the *successor*
of `self`

`count`

times. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the value that would be obtained by taking the *predecessor*
of `self`

`count`

times. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the number of *successor* steps required to get from `start`

to `end`

. Read more

Performs the `-=`

operation. Read more

Performs the `-=`

operation. Read more

Try to create the target number type from a source number type. This returns an error if the source value is outside of the range of the target type.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

Try to create the target number type from a source number type. This returns an error if the source value is outside of the range of the target type.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

Try to create the target number type from a source number type. This returns an error if the source value is outside of the range of the target type.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

## Auto Trait Implementations

## Blanket Implementations

Mutably borrows from an owned value. Read more