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);
Run

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!"),
}
Run

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);
Run

Implementations§

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));
Run
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);
Run

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));
Run
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);
Run

Trait Implementations§

The resulting type after applying the & operator.
Performs the & operation. Read more
The resulting type after applying the & operator.
Performs the & operation. Read more
The resulting type after applying the & operator.
Performs the & operation. Read more
The resulting type after applying the & operator.
Performs the & operation. Read more
The resulting type after applying the & operator.
Performs the & operation. Read more
The resulting type after applying the & operator.
Performs the & operation. Read more
Performs the &= operation. Read more
Performs the &= operation. Read more
Performs the &= operation. Read more
The resulting type after applying the | operator.
Performs the | operation. Read more
The resulting type after applying the | operator.
Performs the | operation. Read more
The resulting type after applying the | operator.
Performs the | operation. Read more
The resulting type after applying the | operator.
Performs the | operation. Read more
The resulting type after applying the | operator.
Performs the | operation. Read more
The resulting type after applying the | operator.
Performs the | operation. Read more
Performs the |= operation. Read more
Performs the |= operation. Read more
Performs the |= operation. Read more
The resulting type after applying the ^ operator.
Performs the ^ operation. Read more
The resulting type after applying the ^ operator.
Performs the ^ operation. Read more
The resulting type after applying the ^ operator.
Performs the ^ operation. Read more
The resulting type after applying the ^ operator.
Performs the ^ operation. Read more
The resulting type after applying the ^ operator.
Performs the ^ operation. Read more
The resulting type after applying the ^ operator.
Performs the ^ operation. Read more
Performs the ^= operation. Read more
Performs the ^= operation. Read more
Performs the ^= operation. Read more
Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more

Returns the default value of false

Formats the value using the given formatter. Read more

Converts a bool into an AtomicBool.

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

Converts bool to f32 losslessly.

Converts bool to f64 losslessly.

Converts a bool to a i128. 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);
Run

Converts a bool to a i16. 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);
Run

Converts a bool to a i32. 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);
Run

Converts a bool to a i64. 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);
Run

Converts a bool to a i8. 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);
Run

Converts a bool to a isize. 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);
Run

Converts a bool to a u128. 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);
Run

Converts a bool to a u16. 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);
Run

Converts a bool to a u32. 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);
Run

Converts a bool to a u64. 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);
Run

Converts a bool to a u8. 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);
Run

Converts a bool to a usize. 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);
Run

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());
Run

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());
Run
The associated error which can be returned from parsing.
Feeds this value into the given Hasher. Read more
Feeds a slice of this type into the given Hasher. Read more
The resulting type after applying the ! operator.
Performs the unary ! operation. Read more
The resulting type after applying the ! operator.
Performs the unary ! operation. Read more
This method returns an Ordering between self and other. Read more
Compares and returns the maximum of two values. Read more
Compares and returns the minimum of two values. Read more
Restrict a value to a certain interval. Read more
This method tests for self and other values to be equal, and is used by ==.
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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 (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
Converts the given value to a String. Read more

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

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

The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
Converts the given value to a String. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.