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7.6.2 Unary minus operator

Visual Studio .NET 2003

For an operation of the form `–x`, unary operator overload resolution (Section 7.2.3) is applied to select a specific operator implementation. The operand is converted to the parameter type of the selected operator, and the type of the result is the return type of the operator. The predefined negation operators are:

• Integer negation:
```int operator –(int x);
long operator –(long x);
```

The result is computed by subtracting `x` from zero. If the value of `x` is the smallest representable value of the operand type (−231 for `int` or −263 for `long`), then the mathematical negation of x is not representable within the operand type. If this occurs within a `checked` context, a `System.OverflowException` is thrown; if it occurs within an `unchecked` context, the result is the value of the operand and the overflow is not reported.

If the operand of the negation operator is of type `uint`, it is converted to type `long`, and the type of the result is `long`. An exception is the rule that permits the `int` value −2147483648 (−231) to be written as a decimal integer literal (Section 2.4.4.2).

If the operand of the negation operator is of type `ulong`, a compile-time error occurs. An exception is the rule that permits the `long` value −9223372036854775808 (−263) to be written as a decimal integer literal (Section 2.4.4.2).

• Floating-point negation:
```float operator –(float x);
double operator –(double x);
```

The result is the value of `x` with its sign inverted. If `x` is NaN, the result is also NaN.

• Decimal negation:
```decimal operator –(decimal x);
```

The result is computed by subtracting `x` from zero. Decimal negation is equivalent to using the unary minus operator of type `System.Decimal`.

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