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# core::traits::Neg

The unary negation operator `-`.

## Signature

```rust theme={null}
pub trait Neg
```

## Examples

An implementation of `Neg` for `Sign`, which allows the use of `-` to
negate its value.

```rust theme={null}
#[derive(Copy, Drop, PartialEq)]
enum Sign {
    Negative,
    Zero,
    Positive,
}

impl SignNeg of Neg {
    fn neg(a: Sign) -> Sign {
        match a {
            Sign::Negative => Sign::Positive,
            Sign::Zero => Sign::Zero,
            Sign::Positive => Sign::Negative,
        }
    }
}

// A negative positive is a negative
assert!(-Sign::Positive == Sign::Negative);
// A double negative is a positive
assert!(-Sign::Negative == Sign::Positive);
// Zero is its own negation
assert!(-Sign::Zero == Sign::Zero);
```

## Trait functions

### neg

Performs the unary `-` operation.

#### Signature

```rust theme={null}
fn neg(a: T) -> T
```

#### Examples

```rust theme={null}
let x: i8 = 1;
assert!(-x == -1);
```