Primitive Type bool

1.0.0 ·
Expand description

The boolean type.

The bool represents a value, which could only be either true or false. If you cast a bool into an integer, true will be 1 and false will be 0.

§Basic usage

bool implements various traits, such as BitAnd, BitOr, Not, etc., which allow us to perform boolean operations using &, | and !.

if requires a bool value as its conditional. assert!, which is an important macro in testing, checks whether an expression is true and panics if it isn’t.

let bool_val = true & false | false;
assert!(!bool_val);
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§Examples

A trivial example of the usage of bool:

let praise_the_borrow_checker = true;

// using the `if` conditional
if praise_the_borrow_checker {
    println!("oh, yeah!");
} else {
    println!("what?!!");
}

// ... or, a match pattern
match praise_the_borrow_checker {
    true => println!("keep praising!"),
    false => println!("you should praise!"),
}
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Also, since bool implements the Copy trait, we don’t have to worry about the move semantics (just like the integer and float primitives).

Now an example of bool cast to integer type:

assert_eq!(true as i32, 1);
assert_eq!(false as i32, 0);
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Implementations§

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impl bool

1.62.0 · source

pub fn then_some<T>(self, t: T) -> Option<T>

Returns Some(t) if the bool is true, or None otherwise.

Arguments passed to then_some are eagerly evaluated; if you are passing the result of a function call, it is recommended to use then, which is lazily evaluated.

§Examples
assert_eq!(false.then_some(0), None);
assert_eq!(true.then_some(0), Some(0));
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let mut a = 0;
let mut function_with_side_effects = || { a += 1; };

true.then_some(function_with_side_effects());
false.then_some(function_with_side_effects());

// `a` is incremented twice because the value passed to `then_some` is
// evaluated eagerly.
assert_eq!(a, 2);
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1.50.0 · source

pub fn then<T, F>(self, f: F) -> Option<T>
where F: FnOnce() -> T,

Returns Some(f()) if the bool is true, or None otherwise.

§Examples
assert_eq!(false.then(|| 0), None);
assert_eq!(true.then(|| 0), Some(0));
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let mut a = 0;

true.then(|| { a += 1; });
false.then(|| { a += 1; });

// `a` is incremented once because the closure is evaluated lazily by
// `then`.
assert_eq!(a, 1);
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Trait Implementations§

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impl BitAnd<&bool> for &bool

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type Output = <bool as BitAnd>::Output

The resulting type after applying the & operator.
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fn bitand(self, other: &bool) -> <bool as BitAnd>::Output

Performs the & operation. Read more
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impl BitAnd<&bool> for bool

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type Output = <bool as BitAnd>::Output

The resulting type after applying the & operator.
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fn bitand(self, other: &bool) -> <bool as BitAnd>::Output

Performs the & operation. Read more
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impl<T, const N: usize> BitAnd<Mask<T, N>> for bool

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type Output = Mask<T, N>

The resulting type after applying the & operator.
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fn bitand(self, rhs: Mask<T, N>) -> Mask<T, N>

Performs the & operation. Read more
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impl<'a> BitAnd<bool> for &'a bool

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type Output = <bool as BitAnd>::Output

The resulting type after applying the & operator.
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fn bitand(self, other: bool) -> <bool as BitAnd>::Output

Performs the & operation. Read more
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impl<T, const N: usize> BitAnd<bool> for Mask<T, N>

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type Output = Mask<T, N>

The resulting type after applying the & operator.
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fn bitand(self, rhs: bool) -> Mask<T, N>

Performs the & operation. Read more
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impl BitAnd for bool

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type Output = bool

The resulting type after applying the & operator.
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fn bitand(self, rhs: bool) -> bool

Performs the & operation. Read more
1.22.0 · source§

impl BitAndAssign<&bool> for bool

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fn bitand_assign(&mut self, other: &bool)

Performs the &= operation. Read more
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impl<T, const N: usize> BitAndAssign<bool> for Mask<T, N>

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fn bitand_assign(&mut self, rhs: bool)

Performs the &= operation. Read more
1.8.0 · source§

impl BitAndAssign for bool

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fn bitand_assign(&mut self, other: bool)

Performs the &= operation. Read more
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impl BitOr<&bool> for &bool

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type Output = <bool as BitOr>::Output

The resulting type after applying the | operator.
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fn bitor(self, other: &bool) -> <bool as BitOr>::Output

Performs the | operation. Read more
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impl BitOr<&bool> for bool

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type Output = <bool as BitOr>::Output

The resulting type after applying the | operator.
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fn bitor(self, other: &bool) -> <bool as BitOr>::Output

Performs the | operation. Read more
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impl<T, const N: usize> BitOr<Mask<T, N>> for bool

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type Output = Mask<T, N>

The resulting type after applying the | operator.
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fn bitor(self, rhs: Mask<T, N>) -> Mask<T, N>

Performs the | operation. Read more
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impl<'a> BitOr<bool> for &'a bool

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type Output = <bool as BitOr>::Output

The resulting type after applying the | operator.
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fn bitor(self, other: bool) -> <bool as BitOr>::Output

Performs the | operation. Read more
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impl<T, const N: usize> BitOr<bool> for Mask<T, N>

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type Output = Mask<T, N>

The resulting type after applying the | operator.
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fn bitor(self, rhs: bool) -> Mask<T, N>

Performs the | operation. Read more
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impl BitOr for bool

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type Output = bool

The resulting type after applying the | operator.
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fn bitor(self, rhs: bool) -> bool

Performs the | operation. Read more
1.22.0 · source§

impl BitOrAssign<&bool> for bool

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fn bitor_assign(&mut self, other: &bool)

Performs the |= operation. Read more
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impl<T, const N: usize> BitOrAssign<bool> for Mask<T, N>

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fn bitor_assign(&mut self, rhs: bool)

Performs the |= operation. Read more
1.8.0 · source§

impl BitOrAssign for bool

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fn bitor_assign(&mut self, other: bool)

Performs the |= operation. Read more
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impl BitXor<&bool> for &bool

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type Output = <bool as BitXor>::Output

The resulting type after applying the ^ operator.
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fn bitxor(self, other: &bool) -> <bool as BitXor>::Output

Performs the ^ operation. Read more
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impl BitXor<&bool> for bool

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type Output = <bool as BitXor>::Output

The resulting type after applying the ^ operator.
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fn bitxor(self, other: &bool) -> <bool as BitXor>::Output

Performs the ^ operation. Read more
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impl<T, const N: usize> BitXor<Mask<T, N>> for bool

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type Output = Mask<T, N>

The resulting type after applying the ^ operator.
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fn bitxor(self, rhs: Mask<T, N>) -> <bool as BitXor<Mask<T, N>>>::Output

Performs the ^ operation. Read more
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impl<'a> BitXor<bool> for &'a bool

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type Output = <bool as BitXor>::Output

The resulting type after applying the ^ operator.
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fn bitxor(self, other: bool) -> <bool as BitXor>::Output

Performs the ^ operation. Read more
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impl<T, const N: usize> BitXor<bool> for Mask<T, N>

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type Output = Mask<T, N>

The resulting type after applying the ^ operator.
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fn bitxor(self, rhs: bool) -> <Mask<T, N> as BitXor<bool>>::Output

Performs the ^ operation. Read more
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impl BitXor for bool

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type Output = bool

The resulting type after applying the ^ operator.
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fn bitxor(self, other: bool) -> bool

Performs the ^ operation. Read more
1.22.0 · source§

impl BitXorAssign<&bool> for bool

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fn bitxor_assign(&mut self, other: &bool)

Performs the ^= operation. Read more
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impl<T, const N: usize> BitXorAssign<bool> for Mask<T, N>

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fn bitxor_assign(&mut self, rhs: bool)

Performs the ^= operation. Read more
1.8.0 · source§

impl BitXorAssign for bool

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fn bitxor_assign(&mut self, other: bool)

Performs the ^= operation. Read more
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impl Clone for bool

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fn clone(&self) -> bool

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for bool

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

Formats the value using the given formatter. Read more
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impl Default for bool

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fn default() -> bool

Returns the default value of false

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impl Display for bool

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

Formats the value using the given formatter. Read more
1.24.0 · source§

impl From<bool> for AtomicBool

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fn from(b: bool) -> AtomicBool

Converts a bool into an AtomicBool.

§Examples
use std::sync::atomic::AtomicBool;
let atomic_bool = AtomicBool::from(true);
assert_eq!(format!("{atomic_bool:?}"), "true")
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1.68.0 · source§

impl From<bool> for f32

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fn from(small: bool) -> f32

Converts a bool to f32 losslessly. The resulting value is positive 0.0 for false and 1.0 for true values.

§Examples
let x: f32 = false.into();
assert_eq!(x, 0.0);
assert!(x.is_sign_positive());

let y: f32 = true.into();
assert_eq!(y, 1.0);
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1.68.0 · source§

impl From<bool> for f64

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fn from(small: bool) -> f64

Converts a bool to f64 losslessly. The resulting value is positive 0.0 for false and 1.0 for true values.

§Examples
let x: f64 = false.into();
assert_eq!(x, 0.0);
assert!(x.is_sign_positive());

let y: f64 = true.into();
assert_eq!(y, 1.0);
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1.28.0 · source§

impl From<bool> for i128

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fn from(small: bool) -> i128

Converts a bool to i128 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(i128::from(true), 1);
assert_eq!(i128::from(false), 0);
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1.28.0 · source§

impl From<bool> for i16

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fn from(small: bool) -> i16

Converts a bool to i16 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(i16::from(true), 1);
assert_eq!(i16::from(false), 0);
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1.28.0 · source§

impl From<bool> for i32

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fn from(small: bool) -> i32

Converts a bool to i32 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(i32::from(true), 1);
assert_eq!(i32::from(false), 0);
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1.28.0 · source§

impl From<bool> for i64

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fn from(small: bool) -> i64

Converts a bool to i64 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(i64::from(true), 1);
assert_eq!(i64::from(false), 0);
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1.28.0 · source§

impl From<bool> for i8

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fn from(small: bool) -> i8

Converts a bool to i8 losslessly. 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);
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1.28.0 · source§

impl From<bool> for isize

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fn from(small: bool) -> isize

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

§Examples
assert_eq!(isize::from(true), 1);
assert_eq!(isize::from(false), 0);
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1.28.0 · source§

impl From<bool> for u128

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fn from(small: bool) -> u128

Converts a bool to u128 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(u128::from(true), 1);
assert_eq!(u128::from(false), 0);
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1.28.0 · source§

impl From<bool> for u16

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fn from(small: bool) -> u16

Converts a bool to u16 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(u16::from(true), 1);
assert_eq!(u16::from(false), 0);
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1.28.0 · source§

impl From<bool> for u32

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fn from(small: bool) -> u32

Converts a bool to u32 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(u32::from(true), 1);
assert_eq!(u32::from(false), 0);
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1.28.0 · source§

impl From<bool> for u64

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fn from(small: bool) -> u64

Converts a bool to u64 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(u64::from(true), 1);
assert_eq!(u64::from(false), 0);
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1.28.0 · source§

impl From<bool> for u8

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fn from(small: bool) -> u8

Converts a bool to u8 losslessly. The resulting value is 0 for false and 1 for true values.

§Examples
assert_eq!(u8::from(true), 1);
assert_eq!(u8::from(false), 0);
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1.28.0 · source§

impl From<bool> for usize

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fn from(small: bool) -> usize

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

§Examples
assert_eq!(usize::from(true), 1);
assert_eq!(usize::from(false), 0);
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impl FromStr for bool

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fn from_str(s: &str) -> Result<bool, ParseBoolError>

Parse a bool from a string.

The only accepted values are "true" and "false". Any other input will return an error.

§Examples
use std::str::FromStr;

assert_eq!(FromStr::from_str("true"), Ok(true));
assert_eq!(FromStr::from_str("false"), Ok(false));
assert!(<bool as FromStr>::from_str("not even a boolean").is_err());
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Note, in many cases, the .parse() method on str is more proper.

assert_eq!("true".parse(), Ok(true));
assert_eq!("false".parse(), Ok(false));
assert!("not even a boolean".parse::<bool>().is_err());
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type Err = ParseBoolError

The associated error which can be returned from parsing.
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impl Hash for bool

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

Feeds this value into the given Hasher. Read more
1.3.0 · source§

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

Feeds a slice of this type into the given Hasher. Read more
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impl Not for &bool

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type Output = <bool as Not>::Output

The resulting type after applying the ! operator.
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fn not(self) -> <bool as Not>::Output

Performs the unary ! operation. Read more
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impl Not for bool

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type Output = bool

The resulting type after applying the ! operator.
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fn not(self) -> bool

Performs the unary ! operation. Read more
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impl Ord for bool

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

This method returns an Ordering between self and other. Read more
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fn min(self, other: bool) -> bool

Compares and returns the minimum of two values. Read more
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fn max(self, other: bool) -> bool

Compares and returns the maximum of two values. Read more
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fn clamp(self, min: bool, max: bool) -> bool

Restrict a value to a certain interval. Read more
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impl PartialEq for bool

const: unstable · source§

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

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &bool) -> bool

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

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fn partial_cmp(&self, other: &bool) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
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fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
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fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
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fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
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fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl ConstParamTy for bool

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impl Copy for bool

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impl Eq for bool

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impl StructuralPartialEq for bool

Auto Trait Implementations§

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impl RefUnwindSafe for bool

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impl Send for bool

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impl Sync for bool

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impl Unpin for bool

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impl UnwindSafe for bool

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T> ToString for T
where T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.