Primitive Type bool

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 always demands a bool value. assert!, being an important macro in testing, checks whether an expression returns true.

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

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!"),
}

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);

Trait Implementations

impl Eq for bool

impl Debug for bool

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

Formats the value using the given formatter.

impl BitXorAssign<bool> for bool

fn bitxor_assign(&mut self, other: bool)

The method for the ^= operator

impl BitOrAssign<bool> for bool

fn bitor_assign(&mut self, other: bool)

The method for the |= operator

impl BitAndAssign<bool> for bool

fn bitand_assign(&mut self, other: bool)

The method for the &= operator

impl BitAnd<bool> for bool

type Output = bool

The resulting type after applying the & operator

fn bitand(self, rhs: bool) -> bool

The method for the & operator

impl<'a> BitAnd<bool> for &'a bool

type Output = bool::Output

The resulting type after applying the & operator

fn bitand(self, other: bool) -> bool::Output

The method for the & operator

impl<'a> BitAnd<&'a bool> for bool

type Output = bool::Output

The resulting type after applying the & operator

fn bitand(self, other: &'a bool) -> bool::Output

The method for the & operator

impl<'a, 'b> BitAnd<&'a bool> for &'b bool

type Output = bool::Output

The resulting type after applying the & operator

fn bitand(self, other: &'a bool) -> bool::Output

The method for the & operator

impl Ord for bool

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

This method returns an Ordering between self and other.

impl Clone for bool

fn clone(&self) -> bool

Returns a deep copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Hash for bool

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

Feeds this value into the state given, updating the hasher as necessary.

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

Feeds a slice of this type into the state provided.

impl BitOr<bool> for bool

type Output = bool

The resulting type after applying the | operator

fn bitor(self, rhs: bool) -> bool

The method for the | operator

impl<'a> BitOr<bool> for &'a bool

type Output = bool::Output

The resulting type after applying the | operator

fn bitor(self, other: bool) -> bool::Output

The method for the | operator

impl<'a> BitOr<&'a bool> for bool

type Output = bool::Output

The resulting type after applying the | operator

fn bitor(self, other: &'a bool) -> bool::Output

The method for the | operator

impl<'a, 'b> BitOr<&'a bool> for &'b bool

type Output = bool::Output

The resulting type after applying the | operator

fn bitor(self, other: &'a bool) -> bool::Output

The method for the | operator

impl Default for bool

fn default() -> bool

Returns the "default value" for a type.

impl PartialOrd<bool> for bool

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

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

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

impl Not for bool

type Output = bool

The resulting type after applying the ! operator

fn not(self) -> bool

The method for the unary ! operator

impl<'a> Not for &'a bool

type Output = bool::Output

The resulting type after applying the ! operator

fn not(self) -> bool::Output

The method for the unary ! operator

impl FromStr for bool

type Err = ParseBoolError

The associated error which can be returned from parsing.

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

Parse a bool from a string.

Yields a Result<bool, ParseBoolError>, because s may or may not actually be parseable.

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());

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());

impl PartialEq<bool> for bool

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

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

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

This method tests for !=.

impl BitXor<bool> for bool

type Output = bool

The resulting type after applying the ^ operator

fn bitxor(self, other: bool) -> bool

The method for the ^ operator

impl<'a> BitXor<bool> for &'a bool

type Output = bool::Output

The resulting type after applying the ^ operator

fn bitxor(self, other: bool) -> bool::Output

The method for the ^ operator

impl<'a> BitXor<&'a bool> for bool

type Output = bool::Output

The resulting type after applying the ^ operator

fn bitxor(self, other: &'a bool) -> bool::Output

The method for the ^ operator

impl<'a, 'b> BitXor<&'a bool> for &'b bool

type Output = bool::Output

The resulting type after applying the ^ operator

fn bitxor(self, other: &'a bool) -> bool::Output

The method for the ^ operator

impl Display for bool

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

Formats the value using the given formatter.