8.5

• Point: An x,y coordinate (for example: 10, 20). Each number must be an integer from
–2,147,483,648 to 2,147,483,647 (inclusive).
• Object: A reference to an interactive object.
Each variable has a unique name. When you use a variable's name in an expression, you're
telling an interactive presentation to go find whatever value is stored in that variable and
use that value in the expression.
For example, let's say you have an integer variable named IntVar that contains the number
6. You can then create the following expression:
Box1.Append(IntVar)
When this expression is executed (or "evaluated"), the interactive presentation will find
the value stored in the variable named "IntVar" (6) and put that value in the box named
"Box1." Afterward, the text box named "Box1" will contain the number 6.
Variables can be very useful. You can use a variable to store information such as the number
of the last page someone visited in a presentation, the end user's name, or the number of
points scored in a game.
Variable names are case-insensitive.
Operators
Operators are symbols (such as + and -) that let you add, subtract, multiply, divide, and
perform many other kinds of operations.
The most important operator is the equals sign, because it enables you to assign a value
to a variable. In the previous example, we could have used the following simple expression
to store the number 6 into the variable IntVar:
IntVar = 6
This expression tells an interactive presentation to store the value after the equals sign
into the variable named "IntVar."
Other operators let you combine or compare numbers and other values. For example:
IntVar = 2 + 4
This example uses two operators: The equals sign and the plus sign. When this expression
is executed, your interactive presentation adds 2 + 4 and puts the result into IntVar.
Use a single equals sign (=) for assignment, and a double equals sign (==) to check values
for equality.
Functions
Functions are commands that let you perform complex operations. Many kinds of functions
exist, but all of them use the same format:
318 | A GUIDE TO QUARKXPRESS 8.5: PLUS EDITION
INTERACTIVE LAYOUTS