Prefix Increment and Decrement Operators

Description

The operand for the prefix increment ++ or the prefix decrement -- operator must be a modifiable lvalue with scalar type. The result is not an lvalue.

The operand of the prefix increment operator is incremented by 1. The resulting value is the result of the unary-expression.

The prefix decrement operator behaves the same way as the prefix increment operator except that a value of one is subtracted from the operand.

For any expression E, the unary expressions ++E and (E+=1) yield the same result. If the value of X is 2, after the expression A=++X is evaluated, A is 3 and X is 3.

Pointers are assumed to point into arrays. Incrementing (or decrementing) a pointer causes the pointer to point to the next (or previous) element. This means, for example, that incrementing a pointer to a structure causes the pointer to point to the next structure, not the next byte within the structure. (Refer also to "Additive Operators" for information on adding to pointers.)