Primitive Type bool1.0.0[−]
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
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
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());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());Runtype Err = ParseBoolError
type Err = ParseBoolError
The associated error which can be returned from parsing.
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
Auto Trait Implementations
impl RefUnwindSafe for bool
impl UnwindSafe for bool
Blanket Implementations
Mutably borrows from an owned value. Read more