post-increment-expression

primary-expression ++

post-decrement-expression

primary-expression --

The operand of a postfix increment or decrement operation must be an expression classified as a variable, a property access, or an indexer access. The result of the operation is a value of the same type as the operand.

If the operand of a postfix increment or decrement operation is a property or indexer access, the property or indexer must have both a get and a set accessor. If this is not the case, a compile-time error occurs.

Unary operator overload resolution (14.2.3) is applied to select a specific operator implementation. Predefined ++ and --operators exist for the following types: sbyte , byte , short , ushort , int , uint , long , ulong , char , float , double , decimal , and any enum type. The predefined ++ operators return the value produced by adding 1 to the operand, and the predefined --operators return the value produced by subtracting 1 from the operand.

The run-time processing of a postfix increment or decrement operation of the form x++ or x--consists of the following steps:

• If x is classified as a variable:
• x is evaluated to produce the variable. The value of x is saved. The selected operator is invoked with the saved value of x as its argument. The value returned by the operator is stored in the location given by the evaluation of x. The saved value of x becomes the result of the operation.
• If x is classified as a property or indexer access:
• The instance expression (if x is not static) and the argument list (if x is an indexer access) associated with x are evaluated, and the results are used in the subsequent get and set accessor invocations. The get accessor of x is invoked and the returned value is saved. The selected operator is invoked with the saved value of x as its argument. The set accessor of x is invoked with the value returned by the operator as its value argument. The saved value of x becomes the result of the operation.

The ++ and --operators also support prefix notation (14.6.5). The result of x++ or x--is the value of x before the operation, whereas the result of ++x or --x is the value of x after the operation. In either case, x itself has the same value after the operation.

An operator ++ or operator --implementation can be invoked using either postfix or prefix notation. It is not possible to have separate operator implementations for the two notations.