System information

About conditional processing 27

String operator

The following table describes the one ColdFusion string operator that is a concatenation

operator:

About conditional processing

So far, all the coding examples shown in this chapter are considered linear coding examples.

Linear code is when ColdFusion executes code starting with the first line on the page, and

processes every line in order. Although you will use linear code in your applications, you will

often write code that performs various actions based on conditions, such as the following:

• Determine whether a user entered a value in a form field.

• Display results based on user input.

• Display messages based on the time of day.

You use conditional processing to customize the behavior of your application. Conditional

processing facilitates decision making and lets you control how the code on a page is processed.

In ColdFusion, you implement conditional processing with flow control tags. These tags are

similar to other programming language control elements, such as

if, then, and else. When

using these tags, you can facilitate decision making in your code. The most fundamental tags used

to control code execution are the

cfif, cfelse, and cfelseif tags. Because you will see and use

these tags in Part II of this manual, the following sections provide a basic introduction on how to

use these tags. For more information about other conditional processing tags, including tags for

looping, see ColdFusion MX Developer’s Guide.

Using the cfif tag to evaluate True or False conditions

To create statements that let you evaluate conditions and perform an action based on the result,

you use the

cfif tag to create a cfif statement. The basic syntax is as follows:

HTML and CFML tags executed if expression is True.

</cfif>

In this example, ColdFusion only executes the code inside the cfif statement if the expression

evaluates to True. To perform actions if the expression is False, you can use the

cfelse tag. For

example, if the following

cfif expression evaluates to False, the code between the cfelse tag and

the ending

cfif tag is processed:

HTML and CFML tags executed if expression is True.

HTML and CFML tags executed if expression is False.

</cfif>

Operator Description

& Concatenates strings.