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# Anonymous method expressions

An anonymous-method-expression is one of two ways of defining an anonymous function. These are further described in §7.15.

Unary operators

The +, -, !, ~, ++, --, cast, and await operators are called the unary operators.

unary-expression:
primary-expression
+ unary-expression
- unary-expression
! unary-expression
~ unary-expression
pre-increment-expression
pre-decrement-expression
cast-expression
await-expression

If the operand of a unary-expression has the compile-time type dynamic, it is dynamically bound (§7.2.2). In this case the compile-time type of the unary-expression is dynamic, and the resolution described below will take place at run-time using the run-time type of the operand.

Unary plus operator

For an operation of the form +x, unary operator overload resolution (§7.3.3) 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 unary plus operators are:

int operator +(int x);
uint operator +(uint x);
long operator +(long x);
ulong operator +(ulong x);
float operator +(float x);
double operator +(double x);
decimal operator +(decimal x);

For each of these operators, the result is simply the value of the operand.

Unary minus operator

For an operation of the form –x, unary operator overload resolution (§7.3.3) 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 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 (§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 (§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.

Logical negation operator

For an operation of the form !x, unary operator overload resolution (§7.3.3) 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. Only one predefined logical negation operator exists:

bool operator !(bool x);

This operator computes the logical negation of the operand: If the operand is true, the result is false. If the operand is false, the result is true.

Bitwise complement operator

For an operation of the form ~x, unary operator overload resolution (§7.3.3) 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 bitwise complement operators are:

int operator ~(int x);
uint operator ~(uint x);
long operator ~(long x);
ulong operator ~(ulong x);

For each of these operators, the result of the operation is the bitwise complement of x.

Every enumeration type E implicitly provides the following bitwise complement operator:

E operator ~(E x);

The result of evaluating ~x, where x is an expression of an enumeration type E with an underlying type U, is exactly the same as evaluating (E)(~(U)x), except that the conversion to E is always performed as if in an unchecked context (§7.6.12).

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