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);RunExamples
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!"),
}RunAlso, 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);RunImplementations§
source§impl bool
impl bool
1.62.0 · sourcepub fn then_some<T>(self, t: T) -> Option<T>
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));Runlet 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);Run1.50.0 · sourcepub fn then<T, F>(self, f: F) -> Option<T>where
F: FnOnce() -> T,
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));Runlet 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);RunTrait Implementations§
source§impl<T, const LANES: usize> BitAnd<Mask<T, LANES>> for boolwhere
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitAnd<Mask<T, LANES>> for boolwhere T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
source§impl<T, const LANES: usize> BitAnd<bool> for Mask<T, LANES>where
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitAnd<bool> for Mask<T, LANES>where T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
1.22.0 · source§impl BitAndAssign<&bool> for bool
impl BitAndAssign<&bool> for bool
source§fn bitand_assign(&mut self, other: &bool)
fn bitand_assign(&mut self, other: &bool)
&= operation. Read moresource§impl<T, const LANES: usize> BitAndAssign<bool> for Mask<T, LANES>where
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitAndAssign<bool> for Mask<T, LANES>where T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
source§fn bitand_assign(&mut self, rhs: bool)
fn bitand_assign(&mut self, rhs: bool)
&= operation. Read more1.8.0 · source§impl BitAndAssign<bool> for bool
impl BitAndAssign<bool> for bool
source§fn bitand_assign(&mut self, other: bool)
fn bitand_assign(&mut self, other: bool)
&= operation. Read moresource§impl<T, const LANES: usize> BitOr<Mask<T, LANES>> for boolwhere
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitOr<Mask<T, LANES>> for boolwhere T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
source§impl<T, const LANES: usize> BitOr<bool> for Mask<T, LANES>where
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitOr<bool> for Mask<T, LANES>where T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
1.22.0 · source§impl BitOrAssign<&bool> for bool
impl BitOrAssign<&bool> for bool
source§fn bitor_assign(&mut self, other: &bool)
fn bitor_assign(&mut self, other: &bool)
|= operation. Read moresource§impl<T, const LANES: usize> BitOrAssign<bool> for Mask<T, LANES>where
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitOrAssign<bool> for Mask<T, LANES>where T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
source§fn bitor_assign(&mut self, rhs: bool)
fn bitor_assign(&mut self, rhs: bool)
|= operation. Read more1.8.0 · source§impl BitOrAssign<bool> for bool
impl BitOrAssign<bool> for bool
source§fn bitor_assign(&mut self, other: bool)
fn bitor_assign(&mut self, other: bool)
|= operation. Read moresource§impl<T, const LANES: usize> BitXor<Mask<T, LANES>> for boolwhere
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitXor<Mask<T, LANES>> for boolwhere T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
source§impl<T, const LANES: usize> BitXor<bool> for Mask<T, LANES>where
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitXor<bool> for Mask<T, LANES>where T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
1.22.0 · source§impl BitXorAssign<&bool> for bool
impl BitXorAssign<&bool> for bool
source§fn bitxor_assign(&mut self, other: &bool)
fn bitxor_assign(&mut self, other: &bool)
^= operation. Read moresource§impl<T, const LANES: usize> BitXorAssign<bool> for Mask<T, LANES>where
T: MaskElement,
LaneCount<LANES>: SupportedLaneCount,
impl<T, const LANES: usize> BitXorAssign<bool> for Mask<T, LANES>where T: MaskElement, LaneCount<LANES>: SupportedLaneCount,
source§fn bitxor_assign(&mut self, rhs: bool)
fn bitxor_assign(&mut self, rhs: bool)
^= operation. Read more1.8.0 · source§impl BitXorAssign<bool> for bool
impl BitXorAssign<bool> for bool
source§fn bitxor_assign(&mut self, other: bool)
fn bitxor_assign(&mut self, other: bool)
^= operation. Read more1.24.0 · source§impl From<bool> for AtomicBool
impl From<bool> for AtomicBool
source§impl FromStr for bool
impl FromStr for bool
source§fn from_str(s: &str) -> Result<bool, ParseBoolError>
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());RunNote, 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());Run