The Increment operator is a special, immediate operator that increments a variable by one and assigns the new value to that same variable. It can only be used in run-time variable expressions. Increment has two forms, pre-increment and post-increment, depending on which side of the variable it appears on. The pre-increment form appears to the left of a variable and the post-increment form appears to the right of a variable. This is extremely useful in programming since there are many situations that call for the incrementing of a variable right before or right after the use of that variable's value. For example:
| Code Block |
|---|
Y := ++X - 4 |
The above shows the pre-increment form; it means "increment before providing the value for the next operation". It increments the value of X by one, writes that result to X and provides that result to the rest of the expression. If X started out as 5 in this example, ++X would store 6 in X, then the expression, 6 - 4 is evaluated, finally writing the result, 2, into Y. After this statement, X equals 6 and Y equals 2.
...