Programming instructions

20 Chapter 2 CFML Basics

In the next example, ColdFusion uses the values of the my_first_name and

my_last_name variables to set the value for the my_full_name variable in the last line of

code. The ampersand (

&) string operator joins the variables, and the space surrounded by

double quotation marks (

" ") adds a space between the variables.

Tip: String values assigned to a variable must be enclosed in single (’) or double (")

quotation marks. Numeric or Boolean values assigned to a variable do not require single or

double quotation marks.

So far all the variable examples shown have been about local variables. Local variables are

variables that you can use only on the current ColdFusion page. As shown in the previous

example, a Variables prefix was used to reference an existing variable on the page. Using a

prefix when referencing a variable is important because ColdFusion supports many types

of variables. The syntax for referencing a local variable is as follows:

variables.variablename

Because ColdFusion lets you use the same name with variables of more than one type,

ColdFusion relies on scope referencing. In scope referencing, you preface the variable’s

name with the scope when you refer to that variable.

Other variables and their scope

ColdFusion supports many types of variables. Each type has it own scope, or where it can

be referenced, and its own way of referencing that variable type. The following table

identifies some of the more common types of variables and their prefixes:

You will use these other types of variables in Part II of this book. For additional

information about variables, see CFML Reference.

Displaying variable output

Output is what remains after the ColdFusion server processes the CFML tags on a page.

Usually the output has two parts:

• Information that the user sees (for example, a confirmation message)

• Information that is stored by the server as a result of processing (for example, user

input collected from a form)

Scope Prefix Description

variables

(local variable)

Variables Variables created using cfset or cfparam. Most often you

define the variable on the current page or on a page that you

include using cfinclude.

Form Form Data entered in tags in an HTML form or ColdFusion form

and processed on the action page.

URL URL Variables passed to a page as URL string parameters.

Query QueryName Variables that are named based on the column names that

you select in the database table. The values are created when

you execute the query that selects data from the database.