Skip to Main Content
Programming ColdFusion MX, 2nd Edition
book

Programming ColdFusion MX, 2nd Edition

by Rob Brooks-Bilson
August 2003
Intermediate to advanced content levelIntermediate to advanced
1140 pages
68h 45m
English
O'Reilly Media, Inc.
Content preview from Programming ColdFusion MX, 2nd Edition

Name

IsDefined

Synopsis

                  
                  IsDefined('variable_name')

Determines if the specified variable exists. Returns true if the specified variable exists or false if it doesn’t. Note that IsDefined( ) replaces the deprecated ParameterExists( ) function. Examples:

<cfset MyVar="Variable">
<cfset Form.MyFormVar="Form Variable">
   
<cfoutput>
<cfif IsDefined('MyVar')>
  Variable MyVar exists:<br> MyVar = #MyVar#
<cfelse>
  No variable called MyVar exists.
</cfif>
<p><cfif IsDefined('MyFormVar')>
  Variable MyFormVar exists:<br> MyFormVar = #MyFormVar#
<cfelse>
  No variable called MyFormVar exists.
</cfif>
<p><cfif IsDefined('Queryname.field')>
  Variable Queryname.Field exists:<br> QueryName.Field = #Queryname.Field#
<cfelse>
  No variable called Queryname.Field exists.
</cfif>
</cfoutput>
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Programming ColdFusion

Programming ColdFusion

Rob Brooks-Bilson

Publisher Resources

ISBN: 0596003803Supplemental ContentErrata Page