User Guide

Dynamic expressions and dynamic variables 91
The IIF function requires the DE function to prevent ColdFusion from evaluating literal strings,
as the following example shows:
<cfoutput>
#IIf(IsDefined("LocalVar"), "LocalVar", DE("The variable is not
defined."))#
</cfoutput>
If you do not enclose the string "The variable is not defined." in a DE function, the IIF function
tries to evaluate the contents of the string as an expression and generates an error (in this case, an
invalid parser construct error).
The
IIF function is useful for incorporating ColdFusion logic in-line in HTML code, but it
entails a processing time penalty in cases where you do not otherwise need dynamic expression
evaluation.
The following example shows using
IIF to alternate table row background color between white
and gray. It also shows the use of the
DE function to prevent ColdFusion from evaluating the color
strings.
<cfoutput>
<table border="1" cellpadding="3">
<cfloop index="i" from="1" to="10">
<tr bgcolor="#IIF( i mod 2 eq 0, DE("white"), DE("gray") )#">
<td>
hello #i#
</td>
</tr>
</cfloop>
</table>
</cfoutput>
This code is more compact than the following example, which does not use IIF or DE:
<cfoutput>
<table border="1" cellpadding="3">
<cfloop index="i" from="1" to="10">
<cfif i mod 2 EQ 0>
<cfset Color = "white">
<cfelse>
<cfset Color = "gray">
</cfif>
<tr bgcolor="#color#">
<td>
hello #i#
</td>
</tr>
</cfloop>
</table>
</cfoutput>